Previous Year Paper

RRB Technician Grade III Official Paper (Held On: 30 Dec, 2024 Shift 3) (Previous Year Paper)

Held in 2024

100 questions90 minutes
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Full Test (100 questions)

Question 1

Ramesh has borrowed an amount of Rs. 2,00,000 from a bank to start a business. How much simple interest will he pay at acrate of 11% per annum after 2 years?  

  1. AOption (a)

    Rs. 44,000

  2. BOption (b)

    Rs. 44,600

  3. COption (c)

    Rs. 46,000

  4. DOption (d)

    Rs. 45,500

View answer & explanation

Correct answer

Answer: (a)A.

Rs. 44,000

Why this answer is correct

Shortcut Trick

Net Interest Percentage = Rate × Time = 11% × 2 = 22%.

Simple Interest = 22% of ₹2,00,000.

⇒ 22 × 2000 = ₹44,000.

∴ The correct answer is ₹44,000.

Alternate Method

Given:

Principal (P) = ₹2,00,000

Rate of Interest (R) = 11% per annum

Time Period (T) = 2 years

Formula Used:

Simple Interest (SI) = (P × R × T) ÷ 100

Calculations:

⇒ SI = (2,00,000 × 11 × 2) ÷ 100

⇒ SI = 2,000 × 11 × 2

⇒ SI = 2,000 × 22

⇒ SI = ₹44,000

∴ The correct answer is ₹44,000.

Additional Information

Total Amount Formula

The total amount (A) to be paid back is the sum of Principal and Simple Interest: A = P + SI.

Nature of Simple Interest

Simple Interest remains constant for every year if the Principal and Rate are unchanged, unlike Compound Interest which increases annually.

SI vs CI Difference for 2 Years

The difference between Compound Interest and Simple Interest for 2 years is given by the formula: Difference = P × (R/100)2.

Question 2

Which of the following statements is correct for a homogeneous mixture of sugar in water?  

  1. AOption (a)

    Water is the solvent. 

  2. BOption (b)

    Both water and sugar are solvents. 

  3. COption (c)

    Sugar is the solvent. 

  4. DOption (d)

    Water is the solute.  

View answer & explanation

Correct answer

Answer: (a)A.

Water is the solvent. 

Why this answer is correct

The Correct answer is Water is the solvent.

Key Points

  • A homogeneous mixture is a mixture in which the composition is uniform throughout, and the components cannot be easily separated.
  • In the case of a mixture of sugar in water, water acts as the solvent, which means it is the substance that dissolves the solute (sugar).
  • The component present in the larger amount in a solution is typically considered the solvent, and water is present in a larger quantity than sugar in this mixture.
  • Sugar, being the substance that is dissolved, is the solute.
  • Water is known as the universal solvent because it can dissolve a vast number of substances, including sugar, salt, and many other compounds.
  • The resulting solution of sugar and water is transparent, and the sugar molecules are evenly distributed throughout the water.
  • Homogeneous mixtures like this one do not separate into distinct phases upon standing.
  • This principle is utilized in various industries, such as the food and beverage industry, where sugar solutions are commonly used.

 Additional Information

  • Both water and sugar are solvents
  • This is incorrect because in a solution, only one component acts as a solvent, and the other as a solute.
  • Water is the solvent in this case, and sugar is the solute. They cannot both be solvents simultaneously.
  • Sugar is the solvent
  • This is incorrect because sugar is the solute, which means it is the substance being dissolved in the solvent (water).
  • Sugar does not have the properties of a universal solvent like water.
  • Water is the solute
  • This is incorrect because water is the solvent, not the solute, as it dissolves the sugar to form a homogeneous mixture.
  • Solutes are present in smaller amounts, whereas solvents are present in larger amounts. In this case, water is present in a larger quantity.

Question 3

(a - b)3 + (b - c)3 + (c - a)3 = ?, which of the following should come in place of ? so that relation always holds true?

  1. AOption (a)

    (a + b + c) (a2 + b2 + c2 - ab - bc - ca)

  2. BOption (b)

    2(a - b) (b - c) (c - a)

  3. COption (c)

    (a - b) (b- c) (c - a)

  4. DOption (d)

    3(a - b) (b - c) (c - a)

View answer & explanation

Correct answer

Answer: (d)D.

3(a - b) (b - c) (c - a)

Why this answer is correct

Shortcut Trick

If the sum of three terms is zero, i.e., x + y + z = 0, then x3 + y3 + z3 = 3xyz.

Let x = (a − b), y = (b − c), and z = (c − a).

Check sum: (a − b) + (b − c) + (c − a) = 0.

∴ (a − b)3 + (b − c)3 + (c − a)3 = 3(a − b)(b − c)(c − a).

∴ The correct answer is 3(a - b) (b - c) (c - a).

Alternate Method

Given: Expression (a − b)3 + (b − c)3 + (c − a)3

Formula Used: Algebraic Identity: a3 + b3 + c3 − 3abc = (a + b + c)(a2 + b2 + c2 − ab − bc − ca)

Calculations:

⇒ Let X = (a − b), Y = (b − c), and Z = (c − a).

⇒ First, calculate the sum X + Y + Z:

⇒ (a − b) + (b − c) + (c − a) = a − a + b − b + c − c = 0.

⇒ According to the identity, if X + Y + Z = 0, then the term (X + Y + Z)(X2 + Y2 + Z2 − XY − YZ − ZX) becomes 0.

⇒ X3 + Y3 + Z3 − 3XYZ = 0

⇒ X3 + Y3 + Z3 = 3XYZ

⇒ Substituting the values back: (a − b)3 + (b − c)3 + (c − a)3 = 3(a − b)(b − c)(c − a).

∴ The correct answer is 3(a - b) (b - c) (c - a).

Additional Information

Standard Algebraic Identity

The expansion of a3 + b3 + c3 − 3abc is always (a + b + c)(a2 + b2 + c2 − ab − bc − ca).

Conditional Identity

If a2 + b2 + c2 − ab − bc − ca = 0, then it implies a = b = c, which also leads to a3 + b3 + c3 = 3abc.

Square Transformation

The term (a2 + b2 + c2 − ab − bc − ca) can be rewritten as ½[(a − b)2 + (b − c)2 + (c − a)2].

Question 4

Lavanya got married 10 years ago. Now her age is 1151\frac{1}{5} times her age at the time of marriage. Her son’s present age is one-tenth of her present age. Find her son’s present age.

  1. AOption (a)

    6 years

  2. BOption (b)

    5 years

  3. COption (c)

    12 years

  4. DOption (d)

    20 years

View answer & explanation

Correct answer

Answer: (a)A.

6 years

Why this answer is correct

Shortcut Trick

Age ratio (Now : Marriage) = 1(1/5) : 1 = 6 : 5

Difference in ratio units = 6 − 5 = 1 unit

Given time difference = 10 years ⇒ 1 unit = 10 years

Lavanya's present age = 6 units = 60 years

Son's age = 1/10 × 60 = 6 years

∴ The correct answer is 6 years.

Alternate Method

Given: Marriage happened 10 years ago. Present age = 6/5 of marriage age. Son's age = 1/10 of present age.

Let marriage age be x years.

⇒ Present age = x + 10

⇒ x + 10 = (6/5) × x

⇒ 5(x + 10) = 6x

⇒ 5x + 50 = 6x

⇒ x = 50 years (Age at marriage)

⇒ Lavanya's present age = 50 + 10 = 60 years

⇒ Son's present age = 60 ÷ 10 = 6 years

∴ The correct answer is 6 years.

Additional Information

Ratio Method for Age

If the ratio of ages is given at two different times, the difference between the ratio parts must correspond to the actual years passed.

Age Difference Property

The numerical difference between the ages of two persons remains constant throughout their lives, regardless of the years passed.

Question 5

Which of the following reactions is an example of double displacement reaction? 

  1. AOption (a)

    Fe(s) + CuSO4 (aq) → FeSO4 (aq) + Cu(s)

  2. BOption (b)

    Pb(s) + CuCl2 (aq) → PbCl2 (aq) + Cu(s)

  3. COption (c)

    Na2SO4 (aq) + BaCl2 (aq) → BaSO4 (s) + 2NaCl (aq)

  4. DOption (d)

    Zn(s) + CuSO4 (aq) → ZnSO4 (aq) + Cu(s)

View answer & explanation

Correct answer

Answer: (c)C.

Na2SO4 (aq) + BaCl2 (aq) → BaSO4 (s) + 2NaCl (aq)

Why this answer is correct

The Correct answer is Na2SO4 (aq) + BaCl2 (aq) → BaSO4 (s) + 2NaCl (aq).

Key Points

  • This reaction is an example of a double displacement reaction, where two compounds exchange their ions to form new compounds.
  • The reaction between sodium sulfate (Na2SO4) and barium chloride (BaCl2) produces two new compounds: barium sulfate (BaSO4) and sodium chloride (NaCl).
  • Barium sulfate (BaSO4) forms as an insoluble precipitate, which is the hallmark of a double displacement reaction.
  • This reaction can be represented as: AB + CD → AD + CB, where ions are exchanged between the reactants.
  • In this case: AB = Na2SO4, CD = BaCl2, AD = BaSO4, and CB = NaCl.
  • The formation of a solid precipitate (BaSO4) confirms the occurrence of a chemical reaction.
  • Double displacement reactions are commonly observed in aqueous solutions and are often used for qualitative analysis in chemistry.

 Additional Information

  • Fe(s) + CuSO4 (aq) → FeSO4 (aq) + Cu(s)
  • This is an example of a single displacement reaction, not a double displacement reaction.
  • In this reaction, iron (Fe) displaces copper (Cu) from copper sulfate (CuSO4) to form iron sulfate (FeSO4) and copper metal (Cu).
  • Pb(s) + CuCl2 (aq) → PbCl2 (aq) + Cu(s)
  • This is also an example of a single displacement reaction.
  • Here, lead (Pb) replaces copper (Cu) in copper chloride (CuCl2) to produce lead chloride (PbCl2) and copper metal (Cu).
  • Zn(s) + CuSO4 (aq) → ZnSO4 (aq) + Cu(s)
  • This is yet another example of a single displacement reaction.
  • In this reaction, zinc (Zn) replaces copper (Cu) in copper sulfate (CuSO4) to form zinc sulfate (ZnSO4) and copper metal (Cu).

Question 6

Based on the English alphabetical order, three of the following four letter-clusters are alike in a certain way and thus form a group. Which letter-cluster does not belong to that group?

(Note: The odd man out is not based on the number of consonants/vowels or their position in the letter cluster)

  1. AOption (a)

    VCJ

  2. BOption (b)

    EMS

  3. COption (c)

    AHO

  4. DOption (d)

    HOV

View answer & explanation

Correct answer

Answer: (b)B.

EMS

Why this answer is correct

Logic follows here is that the first letter and the second letter are increased by 7.

Option 1) VCJ

Option 2) EMS

Does not follow the same logic.

Option 3) AHO

Option 4) HOV

Hence the correct answer is "Option 2"

Question 7

TakeMe2S pace (TM2Space), an innovative space technology firm, is based in which city of India?  

  1. AOption (a)

    New Delhi 

  2. BOption (b)

    Chennai 

  3. COption (c)

    Hyderabad 

  4. DOption (d)

    Kolkata  

View answer & explanation

Correct answer

Answer: (c)C.

Hyderabad 

Why this answer is correct

The correct answer is Hyderabad.

Key Points

  • TakeMe2Space (TM2Space) is an innovative space technology firm based in Hyderabad, India.
  • Hyderabad has emerged as a hub for space technology, startups, and research and development in India.
  • TakeMe2Space specializes in developing advanced space technology and contributes to India's space missions.
  • Hyderabad is home to several prominent organizations like ISRO's National Remote Sensing Centre (NRSC) and the Research Centre Imarat (RCI), which supports the growth of space-related industries.
  • The city provides a robust ecosystem for space startups with access to skilled workforce, infrastructure, and government initiatives.
  • TakeMe2Space also collaborates with other space agencies and organizations to promote satellite development, space exploration, and innovation.
  • Hyderabad's strategic focus on technology and innovation makes it a preferred location for companies like TakeMe2Space.

 Additional Information

  • New Delhi
  • New Delhi is the capital of India and a major hub for policy-making and administration.
  • It is home to ISRO's headquarters and other national-level institutions that contribute to India's space programs.
  • While New Delhi is critical for policy and governance, it is not the base of TakeMe2Space.
  • Chennai
  • Chennai is a key city in southern India and houses the ISRO Propulsion Complex (IPRC), which plays a vital role in space propulsion systems.
  • It has a growing technology sector but is not the location for TakeMe2Space.
  • Kolkata
  • Kolkata, located in eastern India, is known for its rich history and culture but is not a prominent hub for space technology startups.
  • While it has institutions contributing to science and technology, it is not the base for TakeMe2Space.

Question 8

Find one-third part of a number whose one-third part exceeds the one-fifth part by 6. 

  1. AOption (a)

    45

  2. BOption (b)

    24

  3. COption (c)

    5

  4. DOption (d)

    15

View answer & explanation

Correct answer

Answer: (d)D.

15

Why this answer is correct

Given:

One-third part of a number exceeds its one-fifth part by 6.

Formula used:

Let the number be x.

One-third part = x/3

One-fifth part = x/5

Calculations:

According to the question:

⇒ x/3 − x/5 = 6

⇒ (5x − 3x) / 15 = 6

⇒ 2x / 15 = 6

⇒ 2x = 6 × 15

⇒ 2x = 90

⇒ x = 45

Now, find one-third part of the number:

⇒ One-third part = x / 3

⇒ One-third part = 45 / 3

⇒ One-third part = 15

∴ The correct answer is option (4).

Question 9

Which of the following describes dendrites? 

  1. AOption (a)

    Short and unbranched 

  2. BOption (b)

    Short and branched 

  3. COption (c)

    Long and branched  

  4. DOption (d)

    Long and unbranched 

View answer & explanation

Correct answer

Answer: (b)B.

Short and branched 

Why this answer is correct

The Correct answer is Short and branched.

Key Points

  • Dendrites are specialized structures of neurons that are primarily responsible for receiving electrochemical signals from other neurons or sensory inputs.
  • They are typically short and exhibit a branched structure, which increases the surface area for receiving signals.
  • The branching nature of dendrites allows them to form connections with multiple neurons, facilitating the integration of information in the nervous system.
  • Dendrites contain specialized structures called dendritic spines, which are tiny protrusions where synapses are formed with other neurons.
  • They play a crucial role in processes such as learning and memory by strengthening or weakening synaptic connections based on activity.
  • In contrast to axons, which transmit signals away from the neuron, dendrites are primarily involved in receiving and processing incoming signals.

 Additional Information

  • Short and unbranched
  • Neuronal structures like axon terminals may sometimes appear short and unbranched, but this description does not apply to dendrites.
  • Unbranched structures are typically not suited for integrating multiple inputs, which is the primary function of dendrites.
  • Long and branched
  • Axons, not dendrites, are more likely to be long and may occasionally exhibit branching, especially near their terminals.
  • Axons are involved in transmitting signals over long distances, which differs from the function of dendrites.
  • Long and unbranched
  • This description is characteristic of certain axons, which are responsible for conducting signals away from the neuron over long distances.
  • Dendrites, in contrast, are short and branched to facilitate the reception of multiple signals.

Question 10

What is the title of the book by Nandan Kamath that won the Sports Book of the Year award in 2024?

  1. AOption (a)

    Spirit of Sports

  2. BOption (b)

    The Winning Mindset

  3. COption (c)

    Boundary Lab

  4. DOption (d)

    Playing It My Way

View answer & explanation

Correct answer

Answer: (c)C.

Boundary Lab

Why this answer is correct

The Correct answer is Boundary Lab.

Key Points

  • Boundary Lab is the title of the book authored by Nandan Kamath, which won the prestigious Sports Book of the Year award in 2024.
  • The book explores various aspects of sports law, governance, and ethics in the context of modern sports.
  • It is a significant contribution to the understanding of legal and regulatory frameworks in sports, making it highly relevant for those involved in sports administration, athletes, and legal professionals.
  • Nandan Kamath is an eminent sports lawyer and has been actively involved in promoting better governance and legal practices in sports.
  • The award highlights the importance of literature that bridges the gap between sports and legal perspectives, encouraging informed decision-making and ethical conduct in the sports industry.
  • The book has received acclaim for its in-depth analysis and comprehensive approach, making it a valuable resource for academicians, policymakers, and sports enthusiasts.

 Additional Information

  • Spirit of Sports
  • The title suggests a focus on the emotional, cultural, and inspirational aspects of sports, but it is not authored by Nandan Kamath or related to the Sports Book of the Year award in 2024.
  • It might represent a thematic exploration of how sports inspire unity, teamwork, and resilience globally.
  • The Winning Mindset
  • This book likely deals with the psychological aspects of sports, such as focus, determination, and mental preparation, but it is not authored by Nandan Kamath.
  • The concept of a "Winning Mindset" is widely discussed in sports psychology and performance enhancement.
  • Playing It My Way
  • This book is the autobiography of Sachin Tendulkar, the legendary Indian cricketer.
  • It recounts his life and career, but it is unrelated to the Sports Book of the Year award in 2024.
  • Published in 2014, it became a bestseller and provides insights into the life of one of India's greatest sports icons.

Question 11

Refer to the given series and answer the question that follows (all numbers are single-digit numbers only, and all counting is to be done from left to right).

(Left) 2 1 6 8 3 9 5 2 7 6 3 2 9 9 7 3 9 6 4 6 3 2 6 2 2 0 3 4 7 2 (Right)

How many such even digits are there, each of which is immediately preceded by an odd digit and also immediately followed by an odd digit?

  1. AOption (a)

    5

  2. BOption (b)

    2

  3. COption (c)

    3

  4. DOption (d)

    4

View answer & explanation

Correct answer

Answer: (d)D.

4

Why this answer is correct

Given series:

(Left) 2 1 6 8 3 9 5 2 7 6 3 2 9 9 7 3 9 6 4 6 3 2 6 2 2 0 3 4 7 2 (Right)

According to the question, such even digits which are immediately preceded by an odd digit and also immediately followed by an odd digit:

Required condition:  odd - Even - odd 

(Left) 2 1 6 8 3 9 5 2 7 6 3 2 9 9 7 3 9 6 4 6 3 2 6 2 2 0 3 4 7 2 (Right)

Thus, there are four such even digits (2, 6, 2, 4)  which are immediately preceded by an odd digit and also immediately followed by an odd digit

Hence, "Option 4" is the correct answer.

Question 12

Which new initiative was launched by the government on National Sports Day 2024?

  1. AOption (a)

    National Sports Scholarship Scheme

  2. BOption (b)

    Retired Sportsperson Empowerment Training (RESET) Programme

  3. COption (c)

    Fit India Movement

  4. DOption (d)

    National Fitness Challenge

View answer & explanation

Correct answer

Answer: (b)B.

Retired Sportsperson Empowerment Training (RESET) Programme

Why this answer is correct

The correct answer is Retired Sportsperson Empowerment Training (RESET) Programme.

Key Points

  • The Retired Sportsperson Empowerment Training (RESET) Programme was launched by the government on National Sports Day 2024.
  • This initiative is aimed at providing career opportunities, skill development, and financial stability to retired sportspersons.
  • RESET focuses on helping athletes transition from their sports careers to alternative professional fields.
  • The programme includes training in areas such as coaching, sports management, fitness training, and entrepreneurship.
  • It also provides access to certifications, workshops, and mentorship programs to enhance employability.
  • The RESET Programme is part of the government’s efforts to recognize the contribution of athletes and ensure their well-being beyond their playing years.
  • This initiative aligns with the larger vision of promoting sports culture and holistic support for athletes in India.

 Additional Information

  • National Sports Scholarship Scheme
  • This option refers to a hypothetical initiative involving scholarships for athletes.
  • While scholarships are an important part of supporting young athletes, there is no specific announcement of a National Sports Scholarship Scheme in 2024.
  • Fit India Movement
  • The Fit India Movement was launched by the Government of India in August 2019 to encourage citizens to adopt a healthy and active lifestyle.
  • It focuses on fitness awareness and promoting physical activities but is unrelated to the RESET Programme.
  • National Fitness Challenge
  • This option suggests an initiative promoting fitness challenges, but no such specific programme was launched on National Sports Day 2024.
  • The term aligns with general fitness campaigns but does not pertain to the RESET Programme.

Question 13

Identify the name of an alloy formed when mix of copper and tin (Cu and Sn)? 

  1. AOption (a)

    Solder 

  2. BOption (b)

    Gold 

  3. COption (c)

    Brass 

  4. DOption (d)

    Bronze  

View answer & explanation

Correct answer

Answer: (d)D.

Bronze  

Why this answer is correct

The Correct answer is Bronze.

Key Points

  • Bronze is an alloy primarily made of copper (Cu) and tin (Sn). The typical ratio used is approximately 88% copper and 12% tin.
  • This alloy has been in use since the Bronze Age (around 3300 BCE to 1200 BCE), marking a significant advancement in human technology.
  • Bronze is known for its strength, durability, and resistance to corrosion, making it suitable for creating tools, weapons, and sculptures.
  • The addition of tin to copper reduces its melting point and increases its hardness, which are crucial properties for crafting robust materials.
  • It is widely used in the manufacturing of statues, coins, musical instruments, and bearings.
  • Some historical artifacts, such as the famous Bronze sculptures from ancient civilizations, showcase the significance of this alloy in early societies.

 Additional Information

  • Solder
  • Solder is another alloy, commonly composed of tin (Sn) and lead (Pb). It is primarily used in electronics and plumbing for joining metal components.
  • Solder has a low melting point, making it ideal for creating secure connections without damaging sensitive materials.
  • Gold
  • Gold is a pure metal rather than an alloy. It is known for its malleability, ductility, and resistance to tarnish.
  • Gold is widely used in jewelry, electronics, and financial reserves.
  • Brass
  • Brass is another alloy, made of copper (Cu) and zinc (Zn).
  • It is known for its golden appearance and is commonly used in decorative items, musical instruments, and plumbing fittings.

Question 14

In a certain code language, ‘ROAM’ is coded as ‘2835' and ‘MORE’ is coded as ‘4538'. What is the code for A’ in the given code language? 

  1. AOption (a)

    8

  2. BOption (b)

    2

  3. COption (c)

    5

  4. DOption (d)

    3

View answer & explanation

Correct answer

Answer: (b)B.

2

Why this answer is correct

Logic followed here is

Logic : ROM is common in both the language and 3 5 8 is common in both the code.

So, code for A is 2.

Hence the correct answer is option (2).

Question 15

At which event was Ram Charan awarded the title of Ambassador for Indian Art and Culture?

  1. AOption (a)

    Cannes Film Festival 2024

  2. BOption (b)

    International Film Festival of India 2024 

  3. COption (c)

    Toronto International Film Festival 2024

  4. DOption (d)

    Indian Film Festival of Melbourne (IFFM) 2024

View answer & explanation

Correct answer

Answer: (d)D.

Indian Film Festival of Melbourne (IFFM) 2024

Why this answer is correct

The Correct answer is Indian Film Festival of Melbourne (IFFM) 2024.

Key Points

  • The Indian Film Festival of Melbourne (IFFM) is one of the most prestigious film festivals held annually in Melbourne, Australia, celebrating Indian cinema and its global impact.
  • In 2024, renowned actor Ram Charan was honored with the title of Ambassador for Indian Art and Culture.
  • This recognition highlights his contribution to promoting Indian cinema and culture on a global platform.
  • The festival serves as a bridge between Indian and Australian cultural ties, fostering understanding through the medium of films.
  • Ram Charan, known for his remarkable performances in films like RRR, has gained international acclaim, making him a fitting choice for this honor.
  • The IFFM often features screenings, panel discussions, and cultural events, providing a platform for Indian artists to showcase their talents to a global audience.
  • This award not only celebrates Ram Charan's achievements but also emphasizes the growing influence of Indian cinema in the global entertainment industry.

 Additional Information

  • Cannes Film Festival
  • The Cannes Film Festival is an annual film festival held in Cannes, France, showcasing new films from around the world.
  • It is one of the most prestigious and highly publicized events in the global film industry.
  • The festival features categories such as the Palme d'Or, awarded for the best film.
  • Although Indian films are often featured, this event did not host the specific recognition for Ram Charan in 2024.
  • International Film Festival of India (IFFI)
  • The International Film Festival of India (IFFI) is held annually in Goa, India, showcasing the best of Indian and world cinema.
  • It is one of the most significant film festivals in Asia, organized by the Government of India.
  • While IFFI highlights Indian cinema extensively, Ram Charan received his award at the IFFM 2024, not at this event.
  • Toronto International Film Festival (TIFF)
  • The Toronto International Film Festival (TIFF) is one of the largest publicly attended film festivals in the world, held annually in Toronto, Canada.
  • It is known for its diverse lineup of films and often serves as a launchpad for award-season contenders.
  • Although Indian films have been showcased here, Ram Charan's recognition as an ambassador happened at the IFFM 2024.

Question 16

In this question, a statement is followed by two courses of actions, numbered I and II. You must assume everything in the statement to be true and on the basis of the information given in the statement, decide which of the course of action/s logically follow for pursuing.

Statement - In City X, the number of car accidents has spiked recently due to poor road conditions and lack of adequate signage.

I. The city should launch an awareness campaign to educate drivers on safe driving practices.

II. Immediate Road repair and installation of proper signage should be carried out.

  1. AOption (a)

    Both I and II follow

  2. BOption (b)

    Neither I nor II follows 

  3. COption (c)

    Only II follows 

  4. DOption (d)

    Only I follows

View answer & explanation

Correct answer

Answer: (c)C.

Only II follows 

Why this answer is correct

Given:

Statement: In City X, the number of car accidents has spiked recently due to poor road conditions and lack of adequate signage.

Course of Action I: The city should launch an awareness campaign to educate drivers on safe driving practices.

Course of Action II: Immediate Road repair and installation of proper signage should be carried out.

Explanation:

The statement clearly mentions that the car accidents are due to poor road conditions and lack of signage.

Course of Action I suggests an awareness campaign.

While it might be helpful, it doesn't directly address the root causes of the accidents.

Course of Action II suggests immediate road repair and installation of proper signage.

This directly addresses the problems mentioned in the statement.

Therefore, Course of Action II is the logical and effective solution.

∴ Only Course of Action II follows.

Question 17

Two pipes A and B can fill the tank in 40 and 60 minutes, respectively. Both the pipes are opened together. After how many minutes should the pipe B be turned off, so that the tank be fill in 30 minutes?

  1. AOption (a)

    20 min

  2. BOption (b)

    15 min

  3. COption (c)

    28 min

  4. DOption (d)

    25 min

View answer & explanation

Correct answer

Answer: (b)B.

15 min

Why this answer is correct

Shortcut Trick Let Total Capacity of the tank be LCM(40, 60) = 120 units. Efficiency of A = 120 ÷ 40 = 3 units/min | Efficiency of B = 120 ÷ 60 = 2 units/min. Pipe A remains open for the full 30 minutes, filling 3 × 30 = 90 units. Remaining work (120 − 90 = 30 units) is done by Pipe B. Time for Pipe B = 30 ÷ 2 = 15 minutes. ∴ The correct answer is 15 min. Alternate Method Given: Pipe A fills in 40 min, Pipe B fills in 60 min, Total time = 30 min. Formula Used: Total Work = Time × Efficiency.

Person Days Total Work Efficiency

Pipe A 40 120 3

Pipe B 60 2

⇒ Total capacity = 120 units. ⇒ Work done by Pipe A in 30 minutes = 30 × 3 = 90 units. ⇒ Remaining work to be done by Pipe B = 120 − 90 = 30 units. ⇒ Time for which Pipe B was open = 30 ÷ 2 = 15 minutes. ∴ The correct answer is 15 min. Additional Information Pipes and Cisterns Concept If a pipe can fill a tank in x hours and another can empty it in y hours, the net part filled in 1 hour = (1/x − 1/y) where y > x. Work and Wages Wages are always distributed in the ratio of the Efficiency of the workers or the ratio of Work Done by them. Alternate Day Work In alternate work problems, calculate the work done in one cycle (sum of efficiencies) and then find the number of cycles required.

Question 18

Consider a parallel combination of 3 resistors R1, R2 and R2 with currents I1, I[2 and I3, respectively. Which of the following is true? (I = total current, Req = equivalent resistance of the circuit)

  1. AOption (a)

    I = I1 + I2 + I3

  2. BOption (b)

    Req=R3+R2R1R2+R1\rm R_{eq}=R_3+\frac{R_2R_1}{R_2+R_1}

  3. COption (c)

    1I=1I1+1I2+1I3\rm \frac{1}{I}=\frac{1}{I_1}+\frac{1}{I_2}+\frac{1}{I_3}

  4. DOption (d)

    Req=R1+R2R3R2+R3\rm R_{eq}=R_1+\frac{R_2R_3}{R_2+R_3}

View answer & explanation

Correct answer

Answer: (a)A.

I = I1 + I2 + I3

Why this answer is correct

The correct answer is I = I1 + I2 + I3.

Key Points

  • In a parallel circuit, the total current (I) flowing through the circuit is the sum of the currents flowing through each branch. Hence, I = I1 + I2 + I3.
  • The voltage across each resistor in a parallel combination is the same, but the current varies depending on the resistance of each branch.
  • Ohm's Law (V = IR) is used to calculate the current through each resistor when the resistance and voltage are known.
  • In parallel circuits, the total current is distributed among the branches, and this is one of the key characteristics of such circuits.
  • The principle of current conservation is applied here, which states that the total current entering a junction equals the total current leaving the junction.
  • Parallel circuits are commonly used in electrical systems where components need to operate independently, such as in home wiring systems.

 Additional Information

  • R_eq = R3 + (R2R1)/(R2 + R1)
  • This formula is incorrect for calculating the equivalent resistance in a parallel circuit. The correct formula involves the reciprocal of resistances.
  • For two resistors in parallel, the equivalent resistance is given by 1/Req = 1/R1 + 1/R2 + ....
  • 1/I = 1/I1 + 1/I2 + 1/I3
  • This equation is incorrect as it misrepresents the relationship between the total current and individual branch currents in a parallel circuit.
  • The reciprocal rule applies to resistances in parallel, not currents.
  • R_eq = R1 + (R2R3)/(R2 + R3)
  • This formula is also incorrect as it doesn't represent the correct calculation of equivalent resistance in a parallel circuit.
  • In a parallel circuit, the equivalent resistance is always smaller than the smallest individual resistance.

Question 19

What is the value of x for balanced chemical equation 3Fe + xH2O → Fe3O4 + 4H2?

  1. AOption (a)

    3

  2. BOption (b)

    1

  3. COption (c)

    4

  4. DOption (d)

    5

View answer & explanation

Correct answer

Answer: (c)C.

4

Why this answer is correct

The Correct answer is 4.

Key Points

  • To balance the given chemical equation 3Fe + xH2O → Fe3O4 + 4H2, we need to ensure that the number of atoms of each element on both sides of the equation is equal.
  • On the product side, Fe3O4 contains 3 iron (Fe) atoms and 4 oxygen (O) atoms. Additionally, there are 4 molecules of hydrogen gas (H2), which account for 8 hydrogen (H) atoms on the product side.
  • On the reactant side, there are 3 iron (Fe) atoms provided by the 3Fe. However, to balance the 4 oxygen atoms and 8 hydrogen atoms on the product side, we require 4 water molecules (H2O), as each water molecule contains 1 oxygen atom and 2 hydrogen atoms.
  • Thus, the balanced equation becomes: 3Fe + 4H2O → Fe3O4 + 4H2.
  • Here, the value of x = 4, which corresponds to the number of water molecules required to balance the equation.
  • This balanced equation ensures the conservation of mass, as the total number of atoms of each element is the same on both sides.

 Additional Information

  • Importance of Balancing Chemical Equations:
  • Balancing chemical equations ensures the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction.
  • It helps in determining the stoichiometric proportions of reactants and products in a reaction.
  • Balanced equations are essential for calculating the quantities of reactants and products in chemical processes.
  • Fe3O4 (Magnetite):
  • Magnetite is a naturally occurring iron oxide mineral with a chemical formula of Fe3O4.
  • It is widely used as a source of iron in the steel manufacturing industry.
  • Magnetite is also known for its magnetic properties, making it useful in various industrial applications.

Question 20

Which of the following unicellular organism change their shape? 

  1. AOption (a)

    Yeast 

  2. BOption (b)

    Bacteria  

  3. COption (c)

    Paramoecium 

  4. DOption (d)

    Amoeba 

View answer & explanation

Correct answer

Answer: (d)D.

Amoeba 

Why this answer is correct

The Correct answer is Amoeba.

Key Points

  • Amoeba is a unicellular organism that belongs to the phylum Protozoa.
  • It is known for its ability to change its shape continuously by extending and retracting its cytoplasm to form structures called pseudopodia.
  • Pseudopodia are used for movement and capturing food, a process called phagocytosis.
  • This organism is commonly found in freshwater environments such as ponds, lakes, and streams.
  • The cell structure of Amoeba is simple, consisting of a nucleus, cytoplasm, and a flexible cell membrane.
  • Amoebas reproduce through a process called binary fission, where the cell divides into two identical daughter cells.
  • Its ability to change shape is due to the absence of a rigid cell wall, making its membrane highly adaptable.
  • It is an excellent example of how unicellular organisms can carry out all life processes independently.

 Additional Information

  • Yeast
  • Yeast is a unicellular fungus commonly used in the food and beverage industry for fermentation.
  • It reproduces mainly through a process called budding, rather than changing shape like Amoeba.
  • Yeasts are important for making bread, beer, and wine.
  • Bacteria
  • Bacteria are unicellular organisms belonging to the domain Prokaryota.
  • They have a rigid cell wall and generally maintain a fixed shape such as spherical (cocci), rod-shaped (bacilli), or spiral (spirilla).
  • Bacteria are found in diverse environments and play roles in decomposition, nitrogen fixation, and causing diseases.
  • Paramoecium
  • Paramoecium is a unicellular organism belonging to the phylum Ciliophora.
  • It has a fixed slipper-like shape and moves using hair-like structures called cilia.
  • Paramoecium is commonly found in freshwater habitats and feeds on microorganisms like bacteria and algae.

Question 21

Parbati Baruah was awarded the Padma Shri-2024. For which achievement is she known?

  1. AOption (a)

    Tiger conservation

  2. BOption (b)

    Rhino conservation

  3. COption (c)

    Lion conservation

  4. DOption (d)

    First woman mahout 

View answer & explanation

Correct answer

Answer: (d)D.

First woman mahout 

Why this answer is correct

The Correct answer is First woman mahout.

Key Points

  • Parbati Baruah is renowned for being the first woman mahout in India, a remarkable achievement in a field traditionally dominated by men.
  • A mahout is a person who works with, rides, and tends to elephants. In India, mahouts are integral to wildlife conservation, forest management, and religious ceremonies involving elephants.
  • She hails from the state of Assam, a region known for its rich wildlife and cultural connection with elephants.
  • Parbati Baruah has spent years mastering the art of handling elephants and has deep knowledge of their behavior, health, and habitat.
  • Her work has significantly contributed to elephant conservation, particularly in the northeast region of India, which faces challenges due to habitat destruction and human-elephant conflicts.
  • She is celebrated for breaking gender stereotypes in a male-dominated profession and inspiring women to pursue unconventional careers.
  • The recognition of her work by the Padma Shri award in 2024 emphasizes the importance of her contribution to wildlife conservation and cultural heritage.

 Additional Information

  • Tiger conservation
  • Tiger conservation refers to efforts aimed at protecting and increasing the population of tigers, which are endangered due to poaching, habitat loss, and human-wildlife conflict.
  • India is home to the largest population of wild tigers in the world, with conservation programs like Project Tiger launched in 1973.
  • Protected areas such as Ranthambore, Sundarbans, and Bandhavgarh are key tiger habitats.
  • Rhino conservation
  • Rhino conservation focuses on protecting the Indian rhinoceros, commonly found in Assam's Kaziranga National Park.
  • Efforts include anti-poaching measures, habitat preservation, and breeding programs.
  • India has made significant progress in rhino conservation, with the population of the one-horned rhino increasing due to these initiatives.
  • Lion conservation
  • Asiatic lions are primarily found in the Gir Forest National Park in Gujarat, India.
  • Conservation efforts include habitat restoration, anti-poaching measures, and raising public awareness to prevent human-lion conflict.
  • The population of Asiatic lions has shown a steady increase due to these efforts.

Question 22

Which of the following options should come in place of the question mark (?) in the given series based on the English alphabetical order?

HLG, KOJ, NRM, QUP, ?

  1. AOption (a)

    TSX

  2. BOption (b)

    TXS

  3. COption (c)

    XTS

  4. DOption (d)

    XST

View answer & explanation

Correct answer

Answer: (b)B.

TXS

Why this answer is correct

Logic followed here is,

Hence the correct answer is "Option 2"

Question 23

Most mature plant cells have a _____ that helps to maintain the turgidity of the cell and store important substances including wastes. 

  1. AOption (a)

    large central vacuole 

  2. BOption (b)

    chromoplasts 

  3. COption (c)

    leucoplasts 

  4. DOption (d)

    small ribosome 

View answer & explanation

Correct answer

Answer: (a)A.

large central vacuole 

Why this answer is correct

The Correct answer is large central vacuole.

Key Points

  • Most mature plant cells have a large central vacuole, which is a membrane-bound organelle filled with cell sap.
  • The large central vacuole is essential for maintaining the turgidity of the cell, ensuring that the cell remains rigid and supports the plant structure.
  • It plays a vital role in storage, holding water, nutrients, ions, and even waste materials.
  • The vacuole helps in maintaining the osmotic balance within the plant cell, which is crucial for its survival.
  • It contains enzymes that aid in the breakdown of complex molecules and cellular debris, contributing to the cell's detoxification processes.
  • The vacuole also contributes to the plant's defense mechanisms by storing harmful or bitter-tasting compounds to deter herbivores.
  • The vacuole is surrounded by a specialized membrane known as the tonoplast, which helps regulate the movement of substances in and out of the vacuole.
  • In addition, the vacuole can store pigments like anthocyanins, which provide coloration to flowers and fruits, aiding in pollination and seed dispersal.

 Additional Information

  • Chromoplasts
  • Chromoplasts are specialized organelles responsible for storing pigments that give fruits, flowers, and other parts of plants their vivid colors.
  • They play a significant role in attracting pollinators and aiding in seed dispersal.
  • Unlike the large central vacuole, chromoplasts do not maintain turgidity or store waste substances.
  • Leucoplasts
  • Leucoplasts are non-pigmented organelles primarily involved in the storage of starch, oils, and proteins.
  • They are commonly found in non-photosynthetic tissues of plants, such as roots and seeds.
  • Leucoplasts do not contribute to maintaining turgidity or storing waste substances like the central vacuole.
  • Small ribosome
  • Small ribosomes are cellular organelles responsible for protein synthesis.
  • They are present in both plant and animal cells and are not involved in maintaining turgidity or storing substances.
  • Ribosomes are often found floating freely in the cytoplasm or attached to the endoplasmic reticulum.

Question 24

Who took oath as Chief Minister for the second time and the first to assume office after the scrapping of Article 370 in Jammu and Kashmir?

  1. AOption (a)

    Shri Omar Abdullah

  2. BOption (b)

    Shri Farooq Abdullah

  3. COption (c)

    Mehbooba Mufti 

  4. DOption (d)

    Shri Manoj Sinha

View answer & explanation

Correct answer

Answer: (a)A.

Shri Omar Abdullah

Why this answer is correct

The Correct answer is Shri Manoj Sinha.

Key Points

  • Shri Manoj Sinha assumed office as the Lieutenant Governor of Jammu and Kashmir following the scrapping of Article 370.
  • He became the second Chief Minister-level leader to hold office after the abrogation of Article 370, marking a significant transition in the region's political administration.
  • Manoj Sinha is a seasoned politician and former Member of Parliament from the Ghazipur constituency in Uttar Pradesh.
  • His appointment symbolized a shift in governance as Jammu and Kashmir transitioned from a state to a Union Territory.
  • Manoj Sinha is known for his administrative capabilities and focus on development-oriented policies.
  • He succeeded Girish Chandra Murmu, the first Lieutenant Governor of Jammu and Kashmir after it became a Union Territory.
  • Under his leadership, the region witnessed steps toward grassroots democracy and efforts to boost economic growth and infrastructure.

 Additional Information

  • Shri Omar Abdullah
  • Omar Abdullah is the former Chief Minister of Jammu and Kashmir and a prominent leader of the National Conference Party.
  • He served as Chief Minister from 2009 to 2015 but did not assume office after the abrogation of Article 370.
  • He is known for his opposition to the scrapping of Article 370, which granted special status to Jammu and Kashmir.
  • Shri Farooq Abdullah
  • Farooq Abdullah, father of Omar Abdullah, is also a former Chief Minister of Jammu and Kashmir.
  • He is a veteran politician and a member of the National Conference Party.
  • Farooq Abdullah has served multiple terms as Chief Minister but was not in office following the removal of Article 370.
  • Mehbooba Mufti
  • Mehbooba Mufti is the former Chief Minister of Jammu and Kashmir and leader of the PDP (People’s Democratic Party).
  • She was the first woman to hold the Chief Minister position in the region.
  • Her tenure ended before the scrapping of Article 370, and she was a strong critic of the decision to revoke Jammu and Kashmir’s special status.

Question 25

CaO(s) + H2O(I) → Ca(OH)2(aq) + Heat, this reaction is called:

  1. AOption (a)

    Wurtz fittig reaction  

  2. BOption (b)

    combination reaction 

  3. COption (c)

    decomposition reaction 

  4. DOption (d)

    Wurtz reaction 

View answer & explanation

Correct answer

Answer: (b)B.

combination reaction 

Why this answer is correct

The Correct answer is Combination Reaction.

Key Points

  • A combination reaction is a type of chemical reaction where two or more substances combine to form a single product.
  • In the given reaction, CaO (calcium oxide), also known as quicklime, reacts with H2O (water) to form Ca(OH)2 (calcium hydroxide), which is commonly known as slaked lime.
  • The reaction is highly exothermic as it releases a significant amount of heat.
  • The general form of a combination reaction is: A + B → AB.
  • In this reaction, CaO (A) combines with H2O (B) to form Ca(OH)2 (AB).
  • Combination reactions are also called synthesis reactions as they result in the formation of a new compound.
  • The product, calcium hydroxide, is an important compound used in various applications such as whitewashing, water treatment, and soil stabilization.

 Additional Information

  • Wurtz Fitting Reaction
  • The Wurtz Fitting reaction is a chemical reaction where an aromatic halide reacts with an alkyl halide in the presence of metallic sodium in dry ether to form an aromatic hydrocarbon.
  • This reaction is used for the synthesis of alkylbenzenes.
  • It is different from the given reaction and does not involve the combination of substances to form a single product.
  • Decomposition Reaction
  • A decomposition reaction is a chemical reaction where a single compound breaks down into two or more simpler substances.
  • It is the reverse of a combination reaction and often requires the input of energy such as heat, light, or electricity.
  • An example of a decomposition reaction is: 2H2O → 2H2 + O2.
  • Wurtz Reaction
  • The Wurtz reaction involves the reaction of an alkyl halide with metallic sodium in dry ether to form a higher alkane.
  • This reaction is used in organic chemistry for the synthesis of alkanes.
  • It is not related to the combination reaction of calcium oxide and water.

Question 26

Seven people, A, B, E, G, P, Q and R, are sitting in a row, facing north. Only two people sit to the left of B. Only three people sit between B and R. P sits second to the right of B. Only two people sit between P and A. G sits at some place to the right of E but at some place to the left of Q. How many people sit to the right of G?

  1. AOption (a)

    Two

  2. BOption (b)

    One

  3. COption (c)

    Three

  4. DOption (d)

    Four

View answer & explanation

Correct answer

Answer: (c)C.

Three

Why this answer is correct

Given, Seven people, A, B, E, G, P, Q and R, are sitting in a row, facing north.

Only two people sit to the left of B.

Only three people sit between B and R.

P sits second to the right of B.

Only two people sit between P and A.

G sits at some place to the right of E but at some place to the left of Q.

So, three people sit to the right of G.

Hence the correct answer is "Option 3"

Question 27

In a certain code language, 'BEAM' is coded as '9483' and 'DAME' is coded as '9683". What is the code for 'B' in the given code language?

  1. AOption (a)

    9

  2. BOption (b)

    8

  3. COption (c)

    4

  4. DOption (d)

    3

View answer & explanation

Correct answer

Answer: (c)C.

4

Why this answer is correct

Logic followed here is

Logic : EAM is common in both the language and 9 8 3 is common in both the code.

So, code for B is 4.

Hence the correct answer is option (3).

Question 28

Two numbers are respectively 30% and 37% less than a third number. What percentage of the first number is the second number?

  1. AOption (a)

    90%

  2. BOption (b)

    10%

  3. COption (c)

    80%

  4. DOption (d)

    20%

View answer & explanation

Correct answer

Answer: (a)A.

90%

Why this answer is correct

Shortcut Trick

Let the third number be 100.

First number = 100 − 30 = 70

Second number = 100 − 37 = 63

Required percentage = (63 ÷ 70) × 100 = 9 × 10 = 90%

∴ The correct answer is 90%.

Alternate Method

Given:

Let the Third Number (N3) = 100

Formula Used:

Percentage = (Value ÷ Base Value) × 100

Calculations:

⇒ First Number (N1) = 100 − (30% of 100) = 70

⇒ Second Number (N2) = 100 − (37% of 100) = 63

⇒ Required % = (N2 ÷ N1) × 100

⇒ Required % = (63 ÷ 70) × 100

⇒ Required % = 0.9 × 100 = 90%

∴ The correct answer is 90%.

Additional Information

Percentage Base Change

When comparing two numbers relative to a third, always assume the third number as 100 to simplify the calculations of the other two values.

Percentage Decrease Formula

New Value = Original Value × (100 − Decrease%) ÷ 100. This is the direct multiplier method for percentage reduction.

Relative Percentage

To find what percent X is of Y, the formula is (X/Y) × 100. Here, Y is the denominator/base of the comparison.

Question 29

Refer to the given series and answer the question that follows (all numbers are single-digit numbers only, and all counting is to be done from left to right).

(Left) 3 5 5 7 1 6 1 8 8 7 6 2 2 5 9 8 1 1 5 3 3 2 8 1 7 9 2 (Right)

How many such even digits are there each of which is immediately preceded by a perfect square and immediately followed by an odd digit? (Note: 1 will be considered as a perfect square.)

  1. AOption (a)

    4

  2. BOption (b)

    3

  3. COption (c)

    0

  4. DOption (d)

    2

View answer & explanation

Correct answer

Answer: (d)D.

2

Why this answer is correct

Given series:

(Left) 3 5 5 7 1 6 1 8 8 7 6 2 2 5 9 8 1 1 5 3 3 2 8 1 7 9 2 (Right)

According to the question, such even digits which are immediately preceded by perfect square and also immediately followed by an odd digit:

Required condition:  perfect square - Even - odd 

(Left) 3 5 5 7 1 6 1 8 8 7 6 2 2 5 9 8 1 1 5 3 3 2 8 1 7 9 2 (Right)

Thus, there are 2 such even digits which are immediately preceded by a perfect square and also immediately followed by an odd digit

Hence, "Option 4" is the correct answer.

Question 30

While subtracting 4 from −313\frac{-3}{13} the resultant value is:

  1. AOption (a)

    −5113\frac{-51}{13}

  2. BOption (b)

    −5513\frac{-55}{13}

  3. COption (c)

    −5313\frac{-53}{13}

  4. DOption (d)

    −5413\frac{-54}{13}

View answer & explanation

Correct answer

Answer: (b)B.

−5513\frac{-55}{13}

Why this answer is correct

Given:

Value 1 = -3/13

Value 2 = 4

Formula used:

Result = Value 1 − Value 2

Calculations:

Result = -3/13 − 4

⇒ Result = (-3 − (4 × 13)) / 13

⇒ Result = (-3 − 52) / 13

⇒ Result = -55/13

∴ The correct answer is option (2).

Question 31

The greatest number among √2, 31/3, 41/4 is:

  1. AOption (a)

    All are equal  

  2. BOption (b)

    31/3

  3. COption (c)

    √2

  4. DOption (d)

    41/4

View answer & explanation

Correct answer

Answer: (b)B.

31/3

Why this answer is correct

Shortcut Trick To compare surds like 21/2, 31/3, and 41/4, find the LCM of the denominators of the powers (2, 3, 4) = 12. Raise each number to the power of 12: (21/2)12 = 26 = 64; (31/3)12 = 34 = 81; (41/4)12 = 43 = 64. Since 81 is the largest value, the corresponding original number is the greatest. ∴ The correct answer is 31/3. Alternate Method

Given: Numbers are √2, 31/3, and 41/4. Formula: To compare a1/n and b1/m, raise both to the power of LCM(n, m). ⇒ √2 = 21/2 ⇒ 31/3 = 31/3 ⇒ 41/4 = (22)1/4 = 22/4 = 21/2 ⇒ Comparing 21/2 and 31/3: ⇒ LCM of 2 and 3 is 6. ⇒ (21/2)6 = 23 = 8 ⇒ (31/3)6 = 32 = 9 ⇒ Since 9 > 8, 31/3 is the greatest number. ∴ The correct answer is 31/3. Additional Information Comparison of Indices If the powers are in fraction form, convert them to a common denominator using LCM to compare the bases directly. Laws of Surds (am)n = am×n and (a × b)n = an × bn are essential for simplifying radical expressions. Equality of Terms Note that √2 and 41/4 are mathematically equal as (22)1/4 = 22/4 = 21/2.

Question 32

On 30th September 2024, Union Minister for Information and Broadcasting Ashwini Vaishnaw announced that the jury had selected veteran film actor _______ as the recipient of the prestigious Dadasaheb Phalke Lifetime Achievement Award for 2022.

  1. AOption (a)

    Asha Bhosle 

  2. BOption (b)

    Mithun Chakraborty 

  3. COption (c)

    Shah Rukh Khan

  4. DOption (d)

    Rajinikanth 

View answer & explanation

Correct answer

Answer: (b)B.

Mithun Chakraborty 

Why this answer is correct

The Correct answer is Mithun Chakraborty.

Key Points

  • Mithun Chakraborty, a veteran Indian film actor, has been chosen as the recipient of the Dadasaheb Phalke Lifetime Achievement Award for the year 2022. This was announced on 30th September 2024 by Union Minister for Information and Broadcasting, Ashwini Vaishnaw.
  • The Dadasaheb Phalke Award is the highest honor in Indian cinema, instituted by the Government of India in 1969 to commemorate Dadasaheb Phalke, the father of Indian cinema.
  • Mithun Chakraborty is renowned for his contributions to Indian cinema, particularly for his iconic performances in Bollywood and regional films. He has acted in over 350 films in various languages, including Hindi, Bengali, and Tamil.
  • He gained prominence with his National Film Award-winning performance in the film "Mrigayaa" in 1976, directed by Mrinal Sen.
  • He is also celebrated for his role in the dance revolution in Bollywood through his famous film "Disco Dancer" (1982), which made him a cultural icon.
  • Beyond acting, he has served as a politician and has been involved in various social initiatives.
  • This award recognizes his lifetime achievement in the field of Indian cinema and his significant influence on the film industry.

 Additional Information

  • Asha Bhosle
  • Asha Bhosle is a legendary Indian playback singer known for her versatility and a career spanning over seven decades.
  • She holds the Guinness World Record for the most studio recordings, having recorded over 11,000 songs.
  • She has received numerous awards, including the Dadasaheb Phalke Award in 2000.
  • Shah Rukh Khan
  • Shah Rukh Khan, popularly known as the "King of Bollywood", is one of the most successful Indian actors globally.
  • He has appeared in over 80 Bollywood films and is known for his charismatic performances.
  • He has not received the Dadasaheb Phalke Lifetime Achievement Award but has earned numerous other accolades, including 14 Filmfare Awards.
  • Rajinikanth
  • Rajinikanth is one of the most iconic actors in Indian cinema, particularly in the Tamil film industry.
  • He was honored with the Dadasaheb Phalke Award in 2020.
  • His unique style, larger-than-life performances, and philanthropic work have made him a cultural phenomenon.

Question 33

B, C. D, E, F, K and L are sitting around a circular table, facing the centre. D sits to the immediate right of E. Only three people sit between E and L. B sits to the immediate right of C. Only three people sit between D and F when counted from the left of D. How many people sit between K and C when counted from the left of C?  

  1. AOption (a)

    Three

  2. BOption (b)

    Four

  3. COption (c)

    Two

  4. DOption (d)

    One

View answer & explanation

Correct answer

Answer: (c)C.

Two

Why this answer is correct

Given, B, C. D, E, F, K and L are sitting around a circular table, facing the centre.

Only three people sit between D and F when counted from the left of D.

D sits to the immediate right of E.

Only three people sit between E and L.

B sits to the immediate right of C.

And K sits at the remaining place.

There are two people sit between K and C when counted from the left of C. 

Hence the correct answer is "Option 3"

Question 34

Which of the following elements does NOT usually form molecules and is found in its atomic form? 

  1. AOption (a)

    Hydrogen 

  2. BOption (b)

    Oxygen  

  3. COption (c)

    Helium 

  4. DOption (d)

    Nitrogen 

View answer & explanation

Correct answer

Answer: (c)C.

Helium 

Why this answer is correct

The Correct answer is Helium.

Key Points

  • Helium is a noble gas and belongs to Group 18 of the periodic table.
  • Noble gases are characterized by their full valence electron shell, which makes them extremely stable and chemically inert.
  • Due to this inertness, Helium does not typically form molecules and exists as monoatomic particles.
  • It is the second lightest element in the periodic table after hydrogen.
  • Helium is used in various applications such as cryogenics, as a cooling agent in MRI machines, and in balloons and airships due to its lightweight nature.
  • It is the second most abundant element in the universe, primarily produced through nuclear fusion in stars.
  • Helium is non-toxic, non-flammable, and does not react with other elements under normal conditions.

 Additional Information

  • Hydrogen
  • Hydrogen is the lightest element in the periodic table and exists primarily as a diatomic molecule (H₂) under standard conditions.
  • It is highly reactive and can easily form compounds with other elements.
  • Hydrogen is widely used in industries for applications such as fuel cells, ammonia production, and rocket fuel.
  • This element is the most abundant in the universe and plays a critical role in stellar nuclear fusion processes.
  • Oxygen
  • Oxygen exists as a diatomic molecule (O₂) and is essential for life on Earth due to its role in respiration.
  • It is highly reactive and forms oxides with almost all elements.
  • Oxygen is the third most abundant element in the universe and is used in applications such as medical oxygen therapy and industrial processes.
  • Nitrogen
  • Nitrogen is a diatomic molecule (N₂) and makes up about 78% of the Earth's atmosphere.
  • It is relatively inert due to the strong triple bond between its atoms, which makes it useful in preserving food and creating an inert environment for industrial processes.
  • Nitrogen is essential for life and is a key component of amino acids and DNA.
  • It is used in the production of fertilizers, explosives, and cryogenics.

Question 35

Which of the following is/are called biological catalysts? 

  1. AOption (a)

    Hydrochloric acid 

  2. BOption (b)

    Mucus 

  3. COption (c)

    Digestive juices  

  4. DOption (d)

    Enzymes 

View answer & explanation

Correct answer

Answer: (d)D.

Enzymes 

Why this answer is correct

The Correct answer is Enzymes.

Key Points

  • Enzymes are biological molecules that act as catalysts in living organisms.
  • They speed up biochemical reactions by lowering the activation energy required for the reaction to occur.
  • Enzymes are typically made up of proteins, though some RNA molecules can also function as enzymes (e.g., ribozymes).
  • Each enzyme is highly specific to the substrate it acts upon due to the unique structure of its active site.
  • They play a crucial role in various processes such as digestion, respiration, and DNA replication.
  • Examples of enzymes include amylase (breaks down starch), lipase (breaks down fats), and protease (breaks down proteins).
  • Enzymes are sensitive to environmental factors such as temperature and pH, which can affect their activity.

 Additional Information

  • Hydrochloric acid
  • Hydrochloric acid (HCl) is a component of gastric juice in the stomach.
  • It helps in the digestion process by creating an acidic environment, which activates the enzyme pepsin for protein breakdown.
  • HCl also kills bacteria and other pathogens in the food.
  • Mucus
  • Mucus is a slippery secretion produced by mucous membranes in the body.
  • It plays a role in protecting tissues, such as the lining of the stomach, from damage caused by digestive acids and enzymes.
  • Mucus also helps in lubricating food for easier swallowing and movement through the digestive system.
  • Digestive juices
  • Digestive juices are fluids secreted by the digestive organs, including the stomach, pancreas, and intestines.
  • They contain enzymes, such as amylase, lipase, and protease, which help in breaking down carbohydrates, fats, and proteins, respectively.
  • While digestive juices aid digestion, they are not catalysts themselves; instead, they carry enzymes which perform catalytic functions.

Question 36

A and B invest Rs. 30,000 and Rs. 24,000, respectively, for one year. If they get a profit of Rs. 13,500, then the share of A in the profit will be: 

  1. AOption (a)

    Rs. 9450

  2. BOption (b)

    Rs. 9000

  3. COption (c)

    Rs. 7500

  4. DOption (d)

    Rs. 6000

View answer & explanation

Correct answer

Answer: (c)C.

Rs. 7500

Why this answer is correct

Shortcut Trick

Profit ratio is equal to the investment ratio when the time period is constant.

Ratio of Profit (A : B) = 30,000 : 24,000 = 5 : 4.

Total ratio parts = 5 + 4 = 9 units.

9 units = Rs. 13,500 ⇒ 1 unit = 13,500 ÷ 9 = Rs. 1,500.

Share of A = 5 × 1,500 = Rs. 7,500.

∴ The correct answer is Rs. 7,500.

Alternate Method

Given: Investment of A = Rs. 30,000, Investment of B = Rs. 24,000, Total Profit = Rs. 13,500, Time = 1 year. Formulas: Profit Share = Investment × Time | Profit Ratio = (IA × TA) : (IB × TB)

⇒ Profit Ratio (A : B) = (30,000 × 1) : (24,000 × 1) ⇒ Ratio = 30 : 24 = 5 : 4 ⇒ Let A's share be 5x and B's share be 4x ⇒ 5x + 4x = 13,500 ⇒ 9x = 13,500 ⇒ x = 1,500 ⇒ A's Share = 5 × 1,500 = 7,500

∴ The correct answer is Rs. 7,500.

Additional Information

Partnership Concepts

In a simple partnership, the capital is invested for the same period. The profit is distributed in the ratio of their investments.

Compound Partnership

When capitals are invested for different time periods, the profit is distributed in the ratio of (Capital × Time). Profit Ratio = C1T1 : C2T2.

Question 37

The fragmentation method of reproduction is shown in ______

  1. AOption (a)

    Amoeba 

  2. BOption (b)

    Spirogyra  

  3. COption (c)

    Hydra 

  4. DOption (d)

    Plasmodium  

View answer & explanation

Correct answer

Answer: (b)B.

Spirogyra  

Why this answer is correct

The Correct answer is Spirogyra.

Key Points

  • Spirogyra is a genus of filamentous green algae that reproduces by a method called fragmentation.
  • Fragmentation is an asexual mode of reproduction where the filament breaks into smaller fragments, and each fragment grows into a new individual.
  • Spirogyra is commonly found in freshwater habitats like ponds, ditches, and slow-moving streams.
  • The name Spirogyra comes from the characteristic spiral arrangement of its chloroplasts within the cells.
  • Fragmentation occurs naturally in Spirogyra due to mechanical damage or decay of older cells in the filament.
  • This method of reproduction allows rapid multiplication, especially in favorable environmental conditions, ensuring the survival of the species.
  • Spirogyra contributes to the oxygenation of water bodies and serves as a food source for various aquatic organisms.

 Additional Information

  • Amoeba
  • Amoeba reproduces asexually through a process called binary fission, where the parent cell divides into two identical daughter cells.
  • Amoeba is a single-celled organism found in freshwater, soil, and decaying organic matter.
  • It lacks a fixed shape and moves using pseudopodia.
  • Hydra
  • Hydra reproduces both sexually and asexually, but its common mode of asexual reproduction is budding.
  • In budding, a small outgrowth develops on the parent organism, which eventually detaches and becomes a new individual.
  • Hydra is a freshwater organism belonging to the phylum Cnidaria.
  • Plasmodium
  • Plasmodium is a parasitic protozoan that causes malaria in humans.
  • It reproduces asexually through a process called schizogony and sexually in the gut of the Anopheles mosquito.
  • Plasmodium primarily resides in red blood cells and the liver of the host.

Question 38

If the roots of a plant always grow downwards due to geotropism, then the growth of pollen tubes towards ovules is due to ______.

  1. AOption (a)

    hydrotropism 

  2. BOption (b)

    phototropism  

  3. COption (c)

    geotropism 

  4. DOption (d)

    chemotropism  

View answer & explanation

Correct answer

Answer: (d)D.

chemotropism  

Why this answer is correct

The Correct answer is chemotropism.

Key Points

  • Chemotropism refers to the growth or movement of an organism, typically plants, in response to a chemical stimulus.
  • The growth of pollen tubes towards the ovules is guided by the secretion of chemical attractants from the ovules, making it a classic example of chemotropism.
  • This phenomenon ensures that the male gametes carried by the pollen tube reach the ovules for fertilization, facilitating sexual reproduction in plants.
  • Chemotropism is crucial for the process of pollination and fertilization in flowering plants, contributing to the production of seeds and fruits.
  • It is a directional response, meaning the growth of the pollen tube is oriented specifically towards the source of the chemical stimulus.
  • Examples of chemicals involved in this process include calcium ions and other signaling molecules released by the ovules.

 Additional Information

  • Hydrotropism
  • Hydrotropism is the growth or movement of plants in response to water stimuli.
  • An example is the growth of plant roots towards moist areas in the soil to absorb water.
  • It plays a vital role in the plant's ability to locate water sources, especially in arid conditions.
  • Phototropism
  • Phototropism refers to the growth of plants in response to light stimuli.
  • Plants exhibit positive phototropism when their shoots grow towards the light source and negative phototropism when their roots grow away from light.
  • Phototropism is primarily controlled by a plant hormone called auxin.
  • Geotropism
  • Geotropism, also known as gravitropism, refers to a plant's growth in response to gravity.
  • Roots exhibit positive geotropism as they grow downward into the soil, while shoots exhibit negative geotropism by growing upward against the force of gravity.
  • This response ensures that plants maintain their orientation for optimal nutrient and light absorption.

Question 39

Which of the following options should come in place of the question mark (?) in the given series to make it logically complete?

81, 108.6, 136.2, 163.8, ?

  1. AOption (a)

    191.4

  2. BOption (b)

    198.2

  3. COption (c)

    174.8

  4. DOption (d)

    183.6

View answer & explanation

Correct answer

Answer: (a)A.

191.4

Why this answer is correct

Given

81, 108.6, 136.2, 163.8, ? 

Logic follows here is,

Logic 

So, next number is 191.4.

Hence the correct answer is "Option 1"

Question 40

In which of the following situations is potential energy being stored?  

  1. AOption (a)

    Pushing a vehicle on the plane road 

  2. BOption (b)

    Moving a pencil across a table  

  3. COption (c)

    Lighting a matchstick 

  4. DOption (d)

    Stretching a rubber band 

View answer & explanation

Correct answer

Answer: (d)D.

Stretching a rubber band 

Why this answer is correct

The Correct answer is Stretching a rubber band.

Key Points

  • Potential energy is the energy stored within an object due to its position, condition, or configuration.
  • When a rubber band is stretched, it undergoes a change in its configuration, storing elastic potential energy.
  • The energy stored depends on the extent of stretching, governed by the material's elastic properties.
  • Elastic potential energy is a type of mechanical energy that can be released when the object returns to its original shape.
  • This concept is widely applied in various devices, such as springs, slingshots, and bows, which depend on the storage and release of elastic potential energy.
  • Stretching a rubber band demonstrates the principle of energy conservation, where potential energy transforms into other forms, such as kinetic energy, when released.

 Additional Information

  • Pushing a vehicle on a plane road
  • Pushing a vehicle involves kinetic energy, which is the energy of motion, rather than potential energy.
  • The energy exerted here is used to overcome frictional forces and move the vehicle forward.
  • This scenario does not involve storing energy in the system.
  • Moving a pencil across a table
  • Similar to pushing a vehicle, moving a pencil involves kinetic energy instead of potential energy.
  • The energy is applied to overcome surface friction and move the object.
  • No energy is stored in this process.
  • Lighting a matchstick
  • Lighting a matchstick is a process that involves chemical energy, not potential energy.
  • The chemical energy stored in the matchstick is released as heat and light energy when ignited.
  • This scenario does not represent the storage of energy but rather its conversion.

Question 41

By which unit do the successive members of the homogenous series CH4, C2H6, and C3H8 differ from each other?

  1. AOption (a)

    CH2

  2. BOption (b)

    CH4

  3. COption (c)

    CH

  4. DOption (d)

    CH3

View answer & explanation

Correct answer

Answer: (a)A.

CH2

Why this answer is correct

The Correct answer is CH₂.

Key Points

  • The successive members of a homologous series differ by a common unit, which is CH₂.
  • A homologous series is a group of organic compounds that have a similar structure and functional group but differ by a fixed unit in their molecular formula.
  • In the series provided (CH₄, C₂H₆, C₃H₈), the molecular formulas show a successive difference of CH₂ units between each compound.
  • The molecular formula of methane (CH₄) and ethane (C₂H₆) differs by one CH₂ unit, and similarly, ethane (C₂H₆) and propane (C₃H₈) also differ by one CH₂ unit.
  • Each member of a homologous series has similar chemical properties but shows a gradual change in physical properties like boiling point, melting point, and density due to the addition of the CH₂ group.
  • The concept of homologous series is crucial in organic chemistry as it simplifies the study of organic compounds by grouping them into families.

 Additional Information

  • CH₄
  • CH₄, also known as methane, is the simplest alkane and the first member of the alkane homologous series.
  • Methane is a major component of natural gas and is widely used as a fuel source.
  • It is a colorless, odorless gas at room temperature and is a potent greenhouse gas.
  • CH
  • CH is not a stable molecule in the context of hydrocarbons and does not represent a homologous series unit.
  • It is a radical and may exist in some transient chemical reactions.
  • CH₃
  • CH₃ is a methyl group, which is a part of many organic compounds but does not represent the common difference in a homologous series.
  • It is often seen as a substituent or functional group in organic chemistry.

Question 42

The centre of curvature of a concave mirror lies ______ the mirror, whereas it lies ______ the mirror for a convex. mirror. 

  1. AOption (a)

    behind, in front of 

  2. BOption (b)

    in front of, in front 

  3. COption (c)

    in front of, behind 

  4. DOption (d)

    behind, behind 

View answer & explanation

Correct answer

Answer: (c)C.

in front of, behind 

Why this answer is correct

The Correct answer is in front of, behind.

Key Points

  • The centre of curvature of a spherical mirror is the center of the sphere from which the mirror is made.
  • For a concave mirror, the reflecting surface curves inward, and the centre of curvature lies in front of the mirror. This is because the center of the sphere is located on the same side as the reflecting surface.
  • For a convex mirror, the reflecting surface curves outward, and the centre of curvature lies behind the mirror. The center of the sphere is located on the opposite side of the reflecting surface.
  • The pole, radius of curvature, and principal axis are other important terms related to spherical mirrors. These terms help define the geometry and behavior of these mirrors.
  • Understanding the position of the centre of curvature is essential for ray diagrams and calculating focal lengths in optics.

 Additional Information

  • Behind, in front of
  • This option incorrectly states the positions of the centre of curvature for concave and convex mirrors.
  • In a concave mirror, the centre of curvature is always in front, not behind.
  • In front of, in front
  • This option incorrectly suggests that the centre of curvature for both concave and convex mirrors lies in front.
  • However, in a convex mirror, the centre of curvature is behind because the reflecting surface curves outward.
  • Behind, behind
  • This option incorrectly states that the centre of curvature for both types of mirrors is behind.
  • In reality, the concave mirror's centre of curvature is in front, while the convex mirror's is behind.

Question 43

Select the triad which follows the same pattern as that followed by the two triads given below. Both triads follow the same pattern.

UQ-VR-WY 

RN-SO-TV

  1. AOption (a)

    NK-PM-QS 

  2. BOption (b)

    OK-PL-QS 

  3. COption (c)

    OK-PM-QR  

  4. DOption (d)

    NK-PL-QR 

View answer & explanation

Correct answer

Answer: (b)B.

OK-PL-QS 

Why this answer is correct

The logic follow here is:

UQ-VR-WY 

And

RN-SO-TV 

Only Option 2) follow same logic.

OK-PL-QS 

  

Hence, the correct answer is "Option 2".

Question 44

Which of the following forms a common passage for both the sperms and urine in males?

  1. AOption (a)

    Vas deferens 

  2. BOption (b)

    Urethra 

  3. COption (c)

    Scrotum 

  4. DOption (d)

    Urinary bladder 

View answer & explanation

Correct answer

Answer: (b)B.

Urethra 

Why this answer is correct

The Correct answer is Urethra.

Key Points

  • The urethra in males serves as a common passage for both urine and sperm.
  • It is a tube-like structure that connects the urinary bladder to the external part of the body for the excretion of urine.
  • During ejaculation, sperm from the testes passes through the urethra and exits the body.
  • The urethra is part of both the urinary system and the reproductive system in males.
  • This dual function is facilitated by a special muscular valve called the internal urethral sphincter, which prevents urine from mixing with sperm during ejaculation.
  • Located at the tip of the penis, the urethra opens to the outside of the body, allowing for the discharge of fluids.
  • It plays a crucial role in maintaining proper functioning of the male reproductive and urinary systems.

 Additional Information

  • Vas deferens
  • The vas deferens is a tube that transports sperm from the testes to the urethra.
  • It is part of the male reproductive system but does not serve as a passage for urine.
  • The vas deferens plays a role in storing and carrying sperm during ejaculation.
  • Scrotum
  • The scrotum is a pouch-like structure that houses the testes.
  • It maintains the optimal temperature for sperm production but does not function as a passage for urine or sperm.
  • Its primary role is in the reproductive system, ensuring proper functioning of the testes.
  • Urinary bladder
  • The urinary bladder is a muscular organ that stores urine until it is excreted through the urethra.
  • It is part of the urinary system and does not play any role in the passage of sperm.
  • The bladder ensures controlled release of urine from the body through the urethra.

Question 45

At what rate (in percentage) per annum will Rs. 1,300 give Rs. 520 as simple interest in 8 years? 

  1. AOption (a)

    7%

  2. BOption (b)

    8%

  3. COption (c)

    4%

  4. DOption (d)

    5%

View answer & explanation

Correct answer

Answer: (d)D.

5%

Why this answer is correct

Shortcut Trick

Interest for 1 year = 520 ÷ 8 = ₹65.

Rate % = (Interest per year ÷ Principal) × 100.

Rate % = (65 ÷ 1300) × 100 = 5%.

∴ The correct answer is 5%.

Alternate Method

Given:

Principal (P) = ₹1,300

Simple Interest (SI) = ₹520

Time (T) = 8 years

Formula Used:

SI = (P × R × T) ÷ 100

Calculations:

⇒ 520 = (1300 × R × 8) ÷ 100

⇒ 520 = 13 × R × 8

⇒ 520 = 104 × R

⇒ R = 520 ÷ 104

⇒ R = 5%

∴ The correct answer is 5%.

Additional Information

Simple Interest Components

Simple interest is calculated only on the principal amount. Amount (A) = Principal (P) + Interest (SI).

Rate of Interest

The rate of interest is the percentage of the principal charged as interest for a specific period (usually per annum).

Rule of SI

Interest remains constant for every year in Simple Interest if the Principal and Rate are unchanged.

Question 46

Read the given statements and conclusions carefully. You have to take the given statements to be true even if they seem to be at variance from commonly known facts and decide which conclusion(s) logically follow(s) from the given statements.

Statements:

Some pulses are flours.

All biscuits are curds.

All biscuits are flours.

Conclusions:

(I) All flours are curds.

(II) Some biscuits are pulses.

  1. AOption (a)

    Neither conclusion (I) nor (II) follows.

  2. BOption (b)

    Only conclusion (I) follows.

  3. COption (c)

    Both conclusions (I) and (II) follow.

  4. DOption (d)

    Only conclusion (II) follows.

View answer & explanation

Correct answer

Answer: (a)A.

Neither conclusion (I) nor (II) follows.

Why this answer is correct

Statements:

Some pulses are flours.

All biscuits are curds.

All biscuits are flours.

Possible Venn diagram is,

Conclusions:

(I) All flours are curds.→ Not follow (some flour are curds is possible, but we can't say that all flours are curds by the given statement.)

(II) Some biscuits are pulses. → Not follow (As there is no direct link between biscuits and pulses.)

Hence the correct answer is "Option 1"

Additional Information

Question 47

ATP is broken down giving rise to a fixed amount of energy that can drive the endothermic reactions taking place in which cell organelle of a cell?

  1. AOption (a)

    Ribosome

  2. BOption (b)

    Lysosome

  3. COption (c)

    Mitochondria

  4. DOption (d)

    Chloroplast

View answer & explanation

Correct answer

Answer: (c)C.

Mitochondria

Why this answer is correct

The Correct answer is Mitochondria.

Key Points

  • Mitochondria are known as the powerhouses of the cell because they are the site of ATP production, which is the energy currency of the cell.
  • ATP (Adenosine Triphosphate) is synthesized through cellular respiration, primarily in the mitochondria, using energy derived from the breakdown of glucose or other nutrients.
  • The process of ATP production occurs through oxidative phosphorylation in the inner mitochondrial membrane, where the electron transport chain is located.
  • Mitochondria are double-membrane organelles, with the inner membrane folded into structures called cristae, which increase surface area for energy production.
  • The mitochondria are responsible for driving endothermic reactions within the cell by providing the necessary energy through ATP hydrolysis.
  • These organelles are found in most eukaryotic cells and play a crucial role in energy metabolism, as well as other functions such as regulation of the cell cycle and apoptosis.

 Additional Information

  • Ribosome
  • Ribosomes are the sites of protein synthesis in the cell.
  • They are composed of ribosomal RNA (rRNA) and proteins and are found either floating freely in the cytoplasm or attached to the endoplasmic reticulum (forming rough ER).
  • Ribosomes are not directly involved in energy production but play a critical role in translating genetic information into functional proteins.
  • Lysosome
  • Lysosomes are membrane-bound organelles containing digestive enzymes that break down waste materials and cellular debris.
  • They are primarily involved in the degradation and recycling of cellular components and are not directly related to ATP synthesis.
  • Lysosomes are known as the "suicidal bags" of the cell because they can initiate autophagy or programmed cell death under certain conditions.
  • Chloroplast
  • Chloroplasts are found in plant cells and are the sites of photosynthesis, where light energy is converted into chemical energy stored in glucose.
  • While chloroplasts are involved in energy production, they do not produce ATP for cellular processes but instead synthesize glucose, which can be metabolized by mitochondria to generate ATP.
  • Chloroplasts contain the pigment chlorophyll, which captures sunlight, and are unique to plant and algal cells.

Question 48

Select the set in which the numbers are related in the same way as are the numbers of the following sets.

(NOTE: Operations should be performed on the whole numbers, without breaking down the numbers into its constituent digits. E.g. 13 - Operations on 13 such as adding/subtracting/multiplying etc. to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed.)

(12, 38, 26)

(50, 75, 25)

  1. AOption (a)

    (21, 40, 15)

  2. BOption (b)

    (14, 42, 28)

  3. COption (c)

    (8, 32, 7)

  4. DOption (d)

    (9, 28, 16)

View answer & explanation

Correct answer

Answer: (b)B.

(14, 42, 28)

Why this answer is correct

Logic:

First number + Third number = Second number.

Given:

For (12, 38, 26):

12 + 26 = 38.

For (50, 75, 25):

50 + 25 = 75.

Option 1: (21, 40, 15)

21 + 15 = 36, which is not 40.

Option 2: (14, 42, 28)

14 + 28 = 42.

Option 3: (8, 32, 7)

8 + 7 = 15, which is not 32.

Option 4: (9, 28, 16)

9 + 16 = 25, which is not 28.

∴ The set (14, 42, 28) follows the same logic.

Hence the correct answer is "Option 2"

Question 49

A student in a lab noted the pH value of a solution to be 10. Which of the following statements is correct about a solution? 

  1. AOption (a)

    A solution is acidic with a high hydroxide ion concentration. 

  2. BOption (b)

    A solution is acidic with a high hydrogen ion concentration. 

  3. COption (c)

    A solution is basic with a high hydrogen ion concentration. 

  4. DOption (d)

    A solution is basic with a high hydroxide ion concentration. 

View answer & explanation

Correct answer

Answer: (d)D.

A solution is basic with a high hydroxide ion concentration. 

Why this answer is correct

The correct answer is A solution is basic with a high hydroxide ion concentration.

Key Points

  • A solution with a pH value of 10 is classified as basic or alkaline.
  • The pH scale ranges from 0 to 14, where a pH less than 7 indicates an acidic solution, 7 indicates a neutral solution, and greater than 7 indicates a basic solution.
  • A basic solution has a high hydroxide ion concentration (OH⁻) and a lower concentration of hydrogen ions (H⁺).
  • In a solution with a pH of 10, the concentration of hydroxide ions (OH⁻) is much higher than that of hydrogen ions (H⁺).
  • The relationship between pH and hydroxide ion concentration is governed by the equation: pH + pOH = 14, where pOH represents the hydroxide ion concentration.
  • At a pH of 10, the corresponding pOH is 4, indicating a high concentration of hydroxide ions.
  • Basic solutions are commonly associated with substances like soaps, detergents, and baking soda, which have a pH greater than 7.

 Additional Information

  • A solution is acidic with a high hydroxide ion concentration
  • This statement is incorrect because an acidic solution has a high concentration of hydrogen ions (H⁺), not hydroxide ions.
  • Acidic solutions have a pH less than 7 and are typically associated with substances like lemon juice, vinegar, and hydrochloric acid.
  • A solution is acidic with a high hydrogen ion concentration
  • This statement is incorrect because the given solution has a pH of 10, which is in the basic range, not acidic.
  • An acidic solution would have a pH below 7, indicating a higher concentration of H⁺ ions.
  • A solution is basic with a high hydrogen ion concentration
  • This statement is incorrect because a basic solution has a high concentration of hydroxide ions (OH⁻), not hydrogen ions.
  • A high concentration of hydrogen ions is characteristic of an acidic solution.

Question 50

Which of the following chemical reactions represents the displacement reaction?

  1. AOption (a)

    C(s) + O2(g) → CO2(g)

  2. BOption (b)

    CaO(s) + H2O(l) → Ca(OH)2(aq)

  3. COption (c)

    2AgCl(s) → 2Ag(s) + Cl2(g)

  4. DOption (d)

    Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s)

View answer & explanation

Correct answer

Answer: (d)D.

Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s)

Why this answer is correct

The Correct answer is Zn(s) + CuSO4(aq) → ZnSO4(aq) + Cu(s).

Key Points

  • This is a type of displacement reaction, where one element replaces another element in a compound.
  • In this reaction, zinc (Zn) is more reactive than copper (Cu), so zinc replaces copper from copper sulfate (CuSO4) to form zinc sulfate (ZnSO4) and copper.
  • Displacement reactions generally occur when a more reactive metal displaces a less reactive metal from its compound.
  • Zinc belongs to the higher position in the reactivity series compared to copper, making it capable of displacing copper.
  • This reaction is an example of a redox reaction, where oxidation and reduction occur simultaneously. Zinc is oxidized, and copper is reduced.
  • Such reactions are widely used in applications like metal extraction and refining processes.

 Additional Information

  • C(s) + O2(g) → CO2(g)
  • This reaction represents a combustion reaction, not a displacement reaction.
  • Carbon reacts with oxygen to produce carbon dioxide, releasing energy in the form of heat and light.
  • Combustion reactions are commonly used in applications like energy production and are crucial for fuel-based systems.
  • CaO(s) + H2O(l) → Ca(OH)2(aq)
  • This is a combination reaction, where two reactants combine to form a single product.
  • Calcium oxide (CaO), also known as quicklime, reacts with water to form calcium hydroxide (Ca(OH)2), commonly known as slaked lime.
  • Such reactions are widely used in industries, especially in the preparation of lime mortar and water treatment.
  • 2AgCl(s) → 2Ag(s) + Cl2(g)
  • This is a type of decomposition reaction, where a single compound splits into two or more simpler substances.
  • Silver chloride (AgCl) decomposes into silver metal and chlorine gas when exposed to light, a phenomenon called photodecomposition.
  • This reaction is used in photographic processes and demonstrates the sensitivity of certain compounds to light.

Question 51

Select the correct statement related to the characteristics of prokaryotic cell. 

  1. AOption (a)

    Nuclear region is well defined and surrounded by nuclear membrane. 

  2. BOption (b)

    It has more than one chromosome.

  3. COption (c)

    It has a single chromosome.

  4. DOption (d)

    Membrane bound cell organelles are present.

View answer & explanation

Correct answer

Answer: (c)C.

It has a single chromosome.

Why this answer is correct

The Correct answer is It has a single chromosome.

Key Points

  • Prokaryotic cells are simpler and lack a well-defined nucleus.
  • The genetic material in prokaryotes is present in a region called the nucleoid, which is not surrounded by a nuclear membrane.
  • These cells typically have a single, circular chromosome that contains the genetic information needed for cellular processes.
  • Prokaryotic cells do not have membrane-bound organelles such as mitochondria, endoplasmic reticulum, or Golgi apparatus.
  • Examples of prokaryotic cells include bacteria and archaea.
  • The single chromosome in prokaryotes is often associated with plasmids, which are small, circular DNA molecules that can replicate independently.
  • Prokaryotic cells reproduce asexually through processes like binary fission, which allows for rapid multiplication.
  • The simplicity of prokaryotic cells makes them highly adaptable to various environments, including extreme conditions.

 Additional Information

  • Nuclear region is well defined and surrounded by nuclear membrane
  • Prokaryotic cells lack a well-defined nucleus. Instead, their genetic material is located in the nucleoid region, which is not enclosed by a membrane.
  • In contrast, eukaryotic cells possess a nuclear membrane surrounding their genetic material.
  • It has more than one chromosome
  • Prokaryotic cells generally have a single circular chromosome. Multiple chromosomes are a characteristic of eukaryotic cells.
  • Membrane-bound cell organelles are present
  • Prokaryotic cells lack membrane-bound organelles such as mitochondria, chloroplasts, or the endoplasmic reticulum. These features are exclusive to eukaryotic cells.

Question 52

Which of the following after fertilisation grows rapidly and ripens to form a fruit. Meanwhile, the petals, sepals, stamens, style and stigma may shrivel and fall off?

  1. AOption (a)

    Ovule

  2. BOption (b)

    Gynoecium

  3. COption (c)

    Ovary

  4. DOption (d)

    Pistil

View answer & explanation

Correct answer

Answer: (c)C.

Ovary

Why this answer is correct

The Correct answer is Ovary.

Key Points

  • After fertilisation, the ovary begins to grow rapidly and undergoes transformations to eventually form the fruit.
  • The ovary is a reproductive organ in flowering plants (angiosperms) that encloses the ovules.
  • Once fertilisation occurs, the ovules develop into seeds, and the surrounding ovary tissues mature into the fruit.
  • The petals, sepals, stamens, style, and stigma typically shrivel and fall off as they are no longer required for reproductive processes.
  • The transformation of the ovary into fruit ensures the protection and dispersal of the seeds.
  • This process is critical for the plant’s life cycle and plays a vital role in ensuring reproduction and survival.
  • Examples of ovary-to-fruit transformation include the development of mangoes, apples, tomatoes, and oranges.

 Additional Information

  • Ovule
  • The ovule is the structure within the ovary that develops into a seed after fertilisation.
  • It contains the female gametophyte and is the site of fertilisation by the male gamete.
  • While the ovule itself becomes the seed, it does not grow into the fruit.
  • Gynoecium
  • The gynoecium refers to the collective term for the female reproductive structures in a flower, including the ovary, style, and stigma.
  • While it plays a role in reproduction, only the ovary undergoes transformation to form the fruit.
  • Pistil
  • The pistil is the single or compound unit of the gynoecium. It includes the ovary, style, and stigma.
  • While it aids in reproduction, the pistil as a whole does not grow into a fruit; only the ovary does.

Question 53

In a certain code language,

'A + B' means 'A is the mother of B',

'A - B' means 'A is the brother of B',

'A × B' means 'A is the wife of B'

and 'A ÷ B' means 'A is the father of B'.

How is H related to L if 'H + J × K ÷ M - L?

  1. AOption (a)

    Father's mother

  2. BOption (b)

    Mother's mother

  3. COption (c)

    Mother's sister

  4. DOption (d)

    Wife's mother 

View answer & explanation

Correct answer

Answer: (b)B.

Mother's mother

Why this answer is correct

Preparing the family tree using the following symbols:

A is
Symbol+-×÷
Meaningmotherbrotherwifefather
Of B

 

Thus 'H + J × K ÷ M - L means

Here, we can see that H is Mother's mother of L.

Hence, Option (2) is correct.

Question 54

A retailer permits a trade discount of 25%, followed by a cash discount of 8%, on an article. The net percentage of discount is: 

  1. AOption (a)

    31% 

  2. BOption (b)

    32% 

  3. COption (c)

    34% 

  4. DOption (d)

    33% 

View answer & explanation

Correct answer

Answer: (a)A.

31% 

Why this answer is correct

Shortcut Trick

Net Discount % = x + y − (x × y)/100

Here, x = 25 and y = 8

Net Discount % = 25 + 8 − (25 × 8)/100

Net Discount % = 33 − 200/100 = 33 − 2 = 31%

∴ The correct answer is 31%.

Alternate Method

Given:

Trade Discount = 25%

Cash Discount = 8%

Formula used:

Selling Price (SP) = Marked Price (MP) × (100 − D1)% × (100 − D2)%

MP = 100 75 Net SP = 69

−25% (Trade)

−8% (Cash on 75)

Total Discount = 100 − 69 = 31%

Calculation:

Let the Marked Price be 100.

⇒ Price after trade discount = 100 − 25% of 100

⇒ Price after trade discount = 100 − 25 = 75

⇒ Price after cash discount = 75 − 8% of 75

⇒ Price after cash discount = 75 − (8/100) × 75

⇒ Price after cash discount = 75 − 6 = 69

⇒ Net Discount = Marked Price − Final Selling Price

⇒ Net Discount = 100 − 69 = 31

⇒ Net Discount % = (31/100) × 100 = 31%

∴ The correct answer is 31%.

Additional Information

Successive Discount for Three Terms

For three successive discounts a%, b%, and c%, the equivalent discount is [1 − (1 − a/100)(1 − b/100)(1 − c/100)] × 100.

Marked Price and Cost Price Relation

MP/CP = (100 + Profit%)/(100 − Discount%). This is useful when both profit and discount percentages are given.

Effective Discount on Buy X Get Y Free

Discount % = [Free Items / (Free Items + Paid Items)] × 100.

Question 55

What was India’s rank in the 2024 Global Hunger Index (GHI), a tool used to measure and track hunger at the global, regional and national levels? 

  1. AOption (a)

    110

  2. BOption (b)

    119

  3. COption (c)

    105

  4. DOption (d)

    111

View answer & explanation

Correct answer

Answer: (c)C.

105

Why this answer is correct

The Correct answer is 105.

Key Points

  • The Global Hunger Index (GHI) is a tool designed to comprehensively measure and track hunger at the global, regional, and national levels.
  • India was ranked 105th out of 125 countries in the 2024 Global Hunger Index (GHI).
  • The GHI scores are based on four key indicators:
  • Undernourishment: The share of the population with insufficient caloric intake.
  • Child Wasting: The share of children under the age of five who have low weight for their height, reflecting acute undernutrition.
  • Child Stunting: The share of children under the age of five who have low height for their age, reflecting chronic undernutrition.
  • Child Mortality: The mortality rate of children under the age of five.
  • The GHI is published annually by Concern Worldwide and Welthungerhilfe.
  • India's rank highlights the persistent challenges of malnutrition and hunger in the country despite efforts to improve food security and nutrition.
  • The index emphasizes the need for effective policy implementation, increased agricultural productivity, and better nutritional programs to combat hunger.
  • India's ranking in the GHI is often criticized as it brings attention to inequalities in food distribution and the inadequacy of food security measures.

 Additional Information

  • The Global Hunger Index (GHI) is calculated on a scale of 0 to 100, where 0 is the best score (no hunger) and 100 is the worst.
  • The GHI is often used to track progress towards achieving Sustainable Development Goal 2 (Zero Hunger).
  • India has previously ranked poorly in the GHI, which has sparked debates over the accuracy of the methodology used to measure hunger.
  • India's significant population size means that even a small percentage of undernourished individuals translates into a large absolute number of people suffering from hunger.

Question 56

Select the set in which the numbers are related in the same way as are the numbers of the following sets.

(NOTE: Operations should be performed on the whole numbers, without breaking down the numbers into its constituent digits. E.g. 13-Operations on 13 such as adding/subtracting/multiplying etc. to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed.)

(25, 5, 20)

(40, 8, 32)

  1. AOption (a)

    (80, 14, 64)

  2. BOption (b)

    (100, 16, 64)

  3. COption (c)

    (80, 16, 64)

  4. DOption (d)

    (80, 16, 60)

View answer & explanation

Correct answer

Answer: (c)C.

(80, 16, 64)

Why this answer is correct

Logic:

First number - Third number = Second number.

Given:

For (25, 5, 20):

25 - 20 = 5.

For (40, 8, 32):

40 - 32 = 8.

Check each option,

Option 1: (80, 14, 64)

80 - 64 = 16, which is not 14.

Option 2: (100, 16, 64)

100 - 64 = 36, which is not 16.

Option 3: (80, 16, 64)

80 - 64 = 16.

Option 4: (80, 16, 60)

80 - 60 = 20, which is not 16.

∴ The set (80, 16, 64) follows the same logic.

Hence the correct answer is "Option 3"

Question 57

The average of thirteen consecutive integers is 36. If two times the smallest of these 13 integers is added to the largest of these 13 integers, what will be the sum obtained?

  1. AOption (a)

    121

  2. BOption (b)

    110

  3. COption (c)

    102

  4. DOption (d)

    115

View answer & explanation

Correct answer

Answer: (c)C.

102

Why this answer is correct

Shortcut Trick

For consecutive integers, the average is the middle term (7th term).

Smallest term (1st) = Average − ((n − 1) ÷ 2) = 36 − 6 = 30.

Largest term (13th) = Average + ((n − 1) ÷ 2) = 36 + 6 = 42.

Required Sum = (2 × 30) + 42 = 60 + 42 = 102.

∴ The correct answer is 102.

Alternate Method

Given: Number of integers (n) = 13, Average = 36.

Formula: Average of n consecutive integers = (First + Last) ÷ 2 = Middle Term.

⇒ Middle term (7th term) = 36.

⇒ Smallest term = 36 − (7 − 1) = 30.

⇒ Largest term = 36 + (13 − 7) = 42.

⇒ Required Value = (2 × Smallest) + Largest

⇒ Required Value = (2 × 30) + 42 = 60 + 42 = 102.

∴ The correct answer is 102.

Additional Information

Average of Arithmetic Progression

For any series in AP, Average = (First term + Last term) ÷ 2. For odd number of terms, it is exactly the middle term.

Consecutive Integers Property

In a set of n consecutive integers, the difference between the largest and smallest integer is always (n − 1).

Sum of N terms

Sum = Average × Number of terms. For 13 terms with average 36, Sum = 13 × 36 = 468.

Question 58

Read the given statements and conclusions carefully. You have to take the given statements to be true even if they seem to be at variance from commonly known facts and decide which conclusion(s) logically follow(s) from the given statements.

Statements:

Some games are boards.

No board is a dice.

No remote is a game.

Conclusions:

(I) No game is a dice.

(II) Some remotes are boards.

  1. AOption (a)

    Only conclusion (I) follows.

  2. BOption (b)

    Neither conclusion (I) nor (II) follows. 

  3. COption (c)

    Only conclusion (II) follows.

  4. DOption (d)

    Both conclusions (I) and (II) follow.

View answer & explanation

Correct answer

Answer: (b)B.

Neither conclusion (I) nor (II) follows. 

Why this answer is correct

Statements:

Some games are boards.

No board is a dice.

No remote is a game.

Possible Venn diagram is,

Conclusions:

(I) No game is a dice.→ Not follow (We can't say as there is no direct link between game and dice)

(II) Some remotes are boards. → Not follow (We can't say as there is no direct link between remotes and boards.)

Hence the correct answer is "Option 1"

Additional Information

Question 59

Which of the following is NOT an abiotic component of the ecosystem? 

  1. AOption (a)

    Rainfall 

  2. BOption (b)

    Soil 

  3. COption (c)

    Wind 

  4. DOption (d)

    Grass 

View answer & explanation

Correct answer

Answer: (d)D.

Grass 

Why this answer is correct

The Correct answer is Grass.

Key Points

  • Grass is a biotic component of the ecosystem.
  • Biotic components refer to living organisms or once-living organisms in an ecosystem.
  • Grass is a type of plant and plays a significant role as a producer in the food chain.
  • It converts solar energy into chemical energy through the process of photosynthesis.
  • Grass serves as a primary source of food for herbivores, and indirectly for higher trophic levels.
  • Unlike abiotic components, grass interacts with other living organisms such as animals, fungi, and microorganisms in the ecosystem.

 Additional Information

  • Rainfall
  • Rainfall is an abiotic component as it is a non-living factor in the ecosystem.
  • It plays a crucial role in the water cycle and supports plant and animal life by providing essential water.
  • Rainfall impacts soil moisture, vegetation growth, and habitats of various species.
  • Soil
  • Soil is also an abiotic component that provides a medium for plant growth.
  • It contains minerals and organic matter, which are essential for plant nutrition.
  • Soil supports the ecosystem by storing water and nutrients and hosting various microorganisms.
  • Wind
  • Wind is an abiotic factor that influences weather patterns and the distribution of seeds and pollen.
  • It affects temperature regulation and the evaporation of water in ecosystems.
  • Wind also plays a role in shaping landforms through erosion and deposition.

Question 60

D, E. F. G, L, M and N are sitting around a circular table facing the centre. F sits third to the left of L. N sits second to the left of E. L is an immediate neighbour of both D and N. G is not an immediate neighbour of F. How many people sit between M and N when counted from the right of M?  

  1. AOption (a)

    Two

  2. BOption (b)

    One

  3. COption (c)

    Three

  4. DOption (d)

    Four

View answer & explanation

Correct answer

Answer: (a)A.

Two

Why this answer is correct

Given, D, E. F. G, L, M and N are sitting around a circular table facing the centre.

F sits third to the left of L.

L is an immediate neighbour of both D and N.

N sits second to the left of E.

G is not an immediate neighbour of F.

And M sits at the remaining place.

There two people sit between M and N when counted from the right of M.

Hence the correct answer is "Option 1"

Question 61

If the matrix of bone cells contains calcium and phosphorus compounds, then what do we find in the matrix of cartilage? 

  1. AOption (a)

    Proteins and sugars 

  2. BOption (b)

    Phosphorus and sugars 

  3. COption (c)

    Proteins and fats 

  4. DOption (d)

    Calcium and sugars 

View answer & explanation

Correct answer

Answer: (a)A.

Proteins and sugars 

Why this answer is correct

The correct answer is Proteins and sugars.

Key Points

  • The matrix of cartilage is composed mainly of proteins and sugars, which give it its characteristic flexibility and resilience.
  • Cartilage contains a protein called collagen, which provides structural support and tensile strength.
  • It also contains proteoglycans, a combination of proteins and sugars, which help in retaining water and maintaining the elasticity of cartilage.
  • The sugars present are often in the form of glycosaminoglycans (GAGs) like chondroitin sulfate and hyaluronic acid, which contribute to the cushioning and lubrication properties of cartilage.
  • Cartilage is found in areas of the body such as the joints, ear, nose, and respiratory tract, where flexibility and smooth movement are required.
  • Unlike bone, cartilage does not contain calcium and phosphorus, making it softer and more pliable.
  • Cartilage plays a crucial role in the development of the skeletal system and the smooth functioning of joints.

 Additional Information

  • Phosphorus and sugars
  • Phosphorus is primarily found in bones, where it combines with calcium to form calcium phosphate, which provides strength and rigidity to the skeletal system.
  • Cartilage does not rely on phosphorus for its structural composition; it focuses more on proteins and sugars for flexibility.
  • Proteins and fats
  • Fats are not a significant component of cartilage. They are primarily found in adipose tissues and serve as energy reserves.
  • Cartilage requires proteins like collagen and sugars for its structure and function rather than fats.
  • Calcium and sugars
  • Calcium is a major component of bone tissue, not cartilage. It is essential for the hard and rigid structure of bones.
  • Cartilage lacks calcium, which is why it remains flexible and soft compared to bone tissue.

Question 62

The value sin2 θ + cos2 θ - (sec2 θ - tan2 θ) + tanθ cos θ + sin θ is _______

  1. AOption (a)

    sec2 θ

  2. BOption (b)

    -1

  3. COption (c)

    2 sin θ 

  4. DOption (d)

    0

View answer & explanation

Correct answer

Answer: (c)C.

2 sin θ 

Why this answer is correct

Shortcut Trick

Apply trigonometric identities: sin2 θ + cos2 θ = 1 and sec2 θ − tan2 θ = 1.

Expression ⇒ 1 − 1 + tan θ cos θ + sin θ

Since tan θ cos θ = sin θ, the expression becomes 0 + sin θ + sin θ = 2 sin θ.

∴ The correct answer is 2 sin θ.

Alternate Method

Given: sin2 θ + cos2 θ − (sec2 θ − tan2 θ) + tan θ cos θ + sin θ

Formula Used: sin2 θ + cos2 θ = 1; sec2 θ − tan2 θ = 1; tan θ = sin θ / cos θ

⇒ Substitute identities: (1) − (1) + (sin θ / cos θ × cos θ) + sin θ

⇒ 1 − 1 + sin θ + sin θ

⇒ 0 + 2 sin θ

⇒ 2 sin θ

∴ The correct answer is 2 sin θ.

Additional Information

Pythagorean Identities

Fundamental identities include sin2 θ + cos2 θ = 1, 1 + tan2 θ = sec2 θ, and 1 + cot2 θ = cosec2 θ.

Reciprocal Relations

Key relations: tan θ = sin θ / cos θ, sec θ = 1 / cos θ, and cosec θ = 1 / sin θ.

Question 63

Which of the following scientists proposed the ‘Law of Constant Proportions’? 

  1. AOption (a)

    Ernest Rutherford 

  2. BOption (b)

    E Goldstein 

  3. COption (c)

    JJ Thomson 

  4. DOption (d)

    Joseph Proust 

View answer & explanation

Correct answer

Answer: (d)D.

Joseph Proust 

Why this answer is correct

The Correct answer is Joseph Proust.

Key Points

  • Joseph Proust, a French chemist, proposed the 'Law of Constant Proportions', also known as the 'Proust's Law'.
  • This law states that in a chemical substance, the elements are always present in definite proportions by mass, regardless of the source or method of preparation.
  • The law emphasizes that the composition of a pure compound is fixed and does not vary, which is a fundamental concept in chemistry.
  • For example, in water (H₂O), the mass ratio of hydrogen to oxygen is always 1:8, irrespective of whether the water is sourced from a river, a lake, or synthesized in a laboratory.
  • Proust's work laid the foundation for the development of modern chemical stoichiometry and the study of chemical reactions.
  • This law is a crucial part of Dalton's atomic theory, which further validated the idea of fixed atomic ratios in compounds.

 Additional Information

  • Ernest Rutherford
  • Ernest Rutherford, known as the father of nuclear physics, discovered the nucleus of the atom and proposed the Rutherford atomic model.
  • He is famous for his gold foil experiment, which demonstrated that atoms have a small, dense, and positively charged nucleus.
  • His work provided insights into the structure of the atom but was not related to the 'Law of Constant Proportions'.
  • E. Goldstein
  • E. Goldstein is credited with the discovery of canal rays (positively charged rays), leading to the identification of protons.
  • His work focused on atomic structure and the discovery of subatomic particles, not on chemical laws like the 'Law of Constant Proportions'.
  • J.J. Thomson
  • J.J. Thomson discovered the electron and proposed the plum pudding model of the atom.
  • His contributions include the study of cathode rays and the measurement of the charge-to-mass ratio of electrons.
  • Thomson's work was foundational in atomic physics but unrelated to the 'Law of Constant Proportions'.

Question 64

If the cross-sectional area of a conductor is doubled, other factors remaining the same, the resistivity of the conductor will be: 

  1. AOption (a)

    same 

  2. BOption (b)

    halved 

  3. COption (c)

    one fourth 

  4. DOption (d)

    doubled 

View answer & explanation

Correct answer

Answer: (a)A.

same 

Why this answer is correct

The Correct answer is same.

Key Points

  • Resistivity is a material property that measures how strongly a material opposes the flow of electric current.
  • The resistivity of a conductor is dependent only on the material's nature and is independent of its shape and size, such as its cross-sectional area or length.
  • When the cross-sectional area of a conductor is doubled, the resistance is affected (resistance decreases), but the resistivity remains unchanged.
  • This is because resistivity is defined as a constant for a specific material at a given temperature, regardless of changes in its dimensions.
  • The formula for resistivity is ρ = R × (A / L), where ρ represents resistivity, R is resistance, A is the cross-sectional area, and L is the length of the conductor.
  • From the formula, resistivity is independent of the conductor's dimensions; it is solely determined by the intrinsic properties of the material.
  • Thus, doubling the cross-sectional area affects the resistance but does not alter the inherent resistivity of the conductor.

 Additional Information

  • halved
  • Halving the resistivity would imply a change in the fundamental properties of the material, which does not happen by altering the conductor's dimensions.
  • Resistivity is constant for a specific material and is independent of changes in cross-sectional area.
  • one fourth
  • The term one fourth might apply to changes in resistance when the cross-sectional area is quadrupled, but it does not affect resistivity, as resistivity depends solely on the material.
  • doubled
  • Doubling resistivity would require a fundamental alteration of the material properties, which is not related to changes in physical dimensions like cross-sectional area.

Question 65

Study the following chart and answer the question that follows. 

What is the absolute difference between the export by company X in February and export by company Y in April?

  1. AOption (a)

    15 crore 

  2. BOption (b)

    10 crore

  3. COption (c)

    20 crore

  4. DOption (d)

    5 crores 

View answer & explanation

Correct answer

Answer: (c)C.

20 crore

Why this answer is correct

Given:

Chart showing exports of companies X and Y.

Formula used:

Absolute difference = Export of X in Feb - Export of Y in April.

Calculations:

Export of company X in February = 35.

Export of company Y in April = 55.

Difference = 55 - 35 = 20

The difference between the export by company X in February and export by company Y in April is 20 crore.

Question 66

Which of the following is NOT an example of homogeneous mixture? 

  1. AOption (a)

    A mixture of iron nails in water 

  2. BOption (b)

    A mixture of copper sulphate in water 

  3. COption (c)

    A mixture of salt in water 

  4. DOption (d)

    A mixture of sugar in water 

View answer & explanation

Correct answer

Answer: (a)A.

A mixture of iron nails in water 

Why this answer is correct

The Correct answer is A mixture of iron nails in water.

Key Points

  • A homogeneous mixture is a mixture where the composition is uniform throughout, and the components are not visibly distinguishable.
  • A mixture of iron nails in water is not homogeneous because the iron nails do not dissolve in water. Instead, they remain separate and visible, forming a heterogeneous mixture.
  • In a heterogeneous mixture, the components are physically distinct and can often be separated by physical methods such as filtration or decanting.
  • Iron nails are made of metal and are insoluble in water, making the mixture uneven in composition.
  • Examples of homogeneous mixtures include substances like salt water and sugar water, where the solute dissolves completely in the solvent.
  • This distinction between homogeneous and heterogeneous mixtures is important in chemistry for understanding the properties of materials and how they interact.

 Additional Information

  • A mixture of copper sulphate in water
  • Copper sulphate dissolves completely in water, forming a homogeneous solution.
  • It is commonly used in agriculture as a fungicide and in laboratories for experiments.
  • Its blue color is due to the presence of hydrated copper ions.
  • A mixture of salt in water
  • Salt water is a homogeneous mixture where the salt (sodium chloride) dissolves fully in water, forming a uniform solution.
  • It is widely used in cooking, cleaning, and medical applications.
  • A mixture of sugar in water
  • Sugar water is another example of a homogeneous mixture as sugar dissolves completely in water.
  • It is often used in beverages, syrups, and medical oral rehydration solutions.

Question 67

What is the measure of each exterior angle of a regular octagon?  

  1. AOption (a)

    80° 

  2. BOption (b)

    45° 

  3. COption (c)

    30°

  4. DOption (d)

    60°

View answer & explanation

Correct answer

Answer: (b)B.

45° 

Why this answer is correct

Shortcut Trick

For any regular polygon, the sum of all exterior angles is always 360°.

Measure of each exterior angle = 360° ÷ n (where n is the number of sides).

For a regular octagon, n = 8.

⇒ Angle = 360° ÷ 8 = 45°.

∴ The correct answer is 45°.

Alternate Method

Given: Shape is a regular octagon.

Formula Used: Exterior Angle = 360° / n

Calculations:

⇒ Number of sides (n) in an octagon = 8

⇒ Sum of all exterior angles of a polygon = 360°

⇒ Measure of each exterior angle = 360° ÷ 8

⇒ Measure of each exterior angle = 45°

∴ The correct answer is 45°.

Additional Information

Interior Angle Formula

The measure of each interior angle of a regular polygon is given by [(n − 2) × 180°] / n.

Relationship between Angles

At any vertex, the Interior Angle + Exterior Angle = 180° (Linear Pair).

Sum of Interior Angles

The sum of all interior angles of a polygon with n sides is (n − 2) × 180°.

Question 68

A 70 cm long wire is to be cut into two pieces so that one piece will be 25\frac{2}{5} of the other. How many centimetres will the shorter piece be?

  1. AOption (a)

    30cm 

  2. BOption (b)

    10cm 

  3. COption (c)

    20cm 

  4. DOption (d)

    25cm 

View answer & explanation

Correct answer

Answer: (c)C.

20cm 

Why this answer is correct

Given:

Total length of wire = 70 cm

Ratio of one piece to the other = 2/5

Formula used:

Ratio of two pieces = a : b

Length of shorter piece = (a / (a + b)) × Total Length

Calculations:

Let the length of the longer piece be x cm.

Length of the shorter piece = (2/5) × x

⇒ Ratio of pieces = (2/5)x : x

⇒ Ratio = 2 : 5

Sum of ratio parts = 2 + 5 = 7 units

⇒ 7 units = 70 cm

⇒ 1 unit = 10 cm

⇒ Shorter piece (2 units) = 2 × 10

⇒ Shorter piece = 20 cm

∴ The correct answer is option (3).

Question 69

The motion of the moon around the earth is due to the:

  1. AOption (a)

    Centrifugal force 

  2. BOption (b)

    Coriolis force 

  3. COption (c)

    Coulomb force 

  4. DOption (d)

    Centripetal force 

View answer & explanation

Correct answer

Answer: (d)D.

Centripetal force 

Why this answer is correct

The Correct answer is Centripetal force.

Key Points

  • The motion of the moon around the Earth is governed by the centripetal force.
  • Centripetal force is a force that acts toward the center of a circular path, keeping an object in circular motion.
  • In the case of the moon, this force is provided by the gravitational pull of the Earth.
  • The gravitational force acts as the centripetal force, pulling the moon toward the Earth and preventing it from moving off in a straight line due to its inertia.
  • Without this force, the moon would follow a straight-line path into space, as per Newton's first law of motion.
  • The balance between the moon's tangential velocity and the centripetal force keeps it in a stable orbital motion around the Earth.
  • This principle applies to all celestial bodies in orbit, including planets, satellites, and stars in their respective systems.

 Additional Information

  • Centrifugal force
  • Centrifugal force is a fictitious force that appears to act outward on a body in a rotating reference frame.
  • It is not a real force but rather the result of inertia when viewed in a non-inertial, rotating frame.
  • In contrast to the centripetal force, it does not play a role in the moon's motion, as the moon orbits due to the Earth's gravitational pull.
  • Coriolis force
  • The Coriolis force is an apparent force caused by the rotation of the Earth.
  • It primarily affects the motion of objects over large distances, such as air currents and ocean currents, causing them to deflect to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.
  • It is not responsible for the orbital motion of celestial bodies.
  • Coulomb force
  • The Coulomb force refers to the electrostatic force between two charged particles.
  • It has no role in the motion of the moon, as the moon and the Earth interact primarily through gravitational force, not electrostatic force.

Question 70

Which of the following options represents the number of neutrons present in aluminium? 

  1. AOption (a)

    15

  2. BOption (b)

    14

  3. COption (c)

    27

  4. DOption (d)

    13

View answer & explanation

Correct answer

Answer: (b)B.

14

Why this answer is correct

The Correct answer is 14.

Key Points

  • The number of neutrons in an element can be calculated using the formula: Neutrons = Mass Number - Atomic Number.
  • Aluminium (Al) has an atomic number of 13 and a mass number of 27.
  • Using the formula: Neutrons = 27 - 13 = 14.
  • Hence, Aluminium has a total of 14 neutrons.
  • The atomic number represents the number of protons in an element, which is equal to the number of electrons in a neutral atom.
  • The mass number is the sum of the number of protons and neutrons in the nucleus.
  • Aluminium is a widely used metal known for its lightweight, non-corrosive, and ductile properties.

 Additional Information

  • 15
  • The value 15 does not correspond to the number of neutrons in Aluminium.
  • It is important to correctly subtract the atomic number from the mass number to avoid errors.
  • 27
  • 27 is the mass number of Aluminium, not the number of neutrons.
  • The mass number includes the total number of protons and neutrons in the nucleus of an atom.
  • 13
  • 13 is the atomic number of Aluminium, representing the number of protons or electrons in a neutral atom.

Question 71

Which of the following colours of light is bent through a minimum angle when passing through a glass prism? 

  1. AOption (a)

    Green  

  2. BOption (b)

    Blue 

  3. COption (c)

    Violet 

  4. DOption (d)

    Yellow 

View answer & explanation

Correct answer

Answer: (d)D.

Yellow 

Why this answer is correct

The Correct answer is Yellow.

Key Points

  • When light passes through a glass prism, it undergoes refraction, and its constituent colors bend at different angles due to their varying wavelengths.
  • The phenomenon of different colors bending by different amounts is called dispersion of light.
  • Yellow light, which lies in the middle of the visible spectrum, has a wavelength of approximately 570–590 nm.
  • Because the bending of light is inversely proportional to its wavelength, longer wavelengths bend less than shorter wavelengths.
  • Compared to violet, blue, and green light, yellow light is bent through a minimum angle as it has a relatively longer wavelength.
  • This property of light is significant in optics, including in the design of prisms and lenses.

 Additional Information

  • Green Light
  • Green light has a shorter wavelength than yellow light, approximately 495–570 nm.
  • Because of its shorter wavelength, it bends more than yellow light when passing through a prism.
  • Green light is situated in the middle of the visible spectrum and contributes to the perception of white light.
  • Blue Light
  • Blue light has a wavelength range of 450–495 nm, shorter than both green and yellow light.
  • Due to its shorter wavelength, it bends more than green and yellow light when refracted through a prism.
  • Blue light is commonly associated with technologies such as LED screens and smartphones.
  • Violet Light
  • Violet light has the shortest wavelength in the visible spectrum, approximately 380–450 nm.
  • As a result, violet light bends the most among all visible colors when it passes through a prism.
  • It is located at the extreme end of the visible spectrum and is responsible for the highest level of dispersion in white light.

Question 72

What will come in the place of the question mark ‘?” in the following equation, if ‘+ and ‘÷’ are interchanged and ‘×’ and ‘-’ are interchanged?  

11 ÷ 12 + 4 - 5 × 6 = ?

  1. AOption (a)

    16

  2. BOption (b)

    28

  3. COption (c)

    20

  4. DOption (d)

    22

View answer & explanation

Correct answer

Answer: (c)C.

20

Why this answer is correct

Given Equation: 

11 ÷ 12 + 4 - 5 × 6 = ?

BODMAS Rule:

After interchanging  ‘+' and ‘÷' and ‘×' and ‘-’, we get

11 + 12 ÷ 4 × 5 - 6 

⇒ 11 + 3 × 5 - 6 

⇒ 11 + 15 - 6 = 20

Hence, the correct option is "Option 3".

Question 73

After getting two successive discounts, a shirt with a list price of Rs. 150 is available at Rs. 105. If the second discount is 12.5%, then find the first discount.  

  1. AOption (a)

    25%

  2. BOption (b)

    15%

  3. COption (c)

    12%

  4. DOption (d)

    20%

View answer & explanation

Correct answer

Answer: (d)D.

20%

Why this answer is correct

Shortcut Trick

List Price = 150, Final SP = 105. Total multiplier = 105 ÷ 150 = 0.7.

Second discount = 12.5% ⇒ Multiplier = (100 − 12.5) ÷ 100 = 0.875.

First discount multiplier = Total multiplier ÷ Second multiplier = 0.7 ÷ 0.875 = 0.8.

First discount % = (1 − 0.8) × 100 = 20%.

∴ The correct answer is 20%.

Alternate Method

Given → List Price (MP) = Rs. 150, Final Selling Price (SP) = Rs. 105, Second Discount (d2) = 12.5%. Formulas: SP = MP × (100 − d1)/100 × (100 − d2)/100

⇒ Let the First Discount be x%.

⇒ Price after first discount = 150 × (100 − x)/100.

⇒ Final Price = [150 × (100 − x)/100] × (100 − 12.5)/100 = 105.

⇒ 150 × [(100 − x)/100] × 87.5/100 = 105.

⇒ (100 − x)/100 = (105 × 100) ÷ (150 × 87.5) = 10500 ÷ 13125 = 0.8.

⇒ 100 − x = 80 ⇒ x = 20%.

∴ The correct answer is 20%.

Additional Information

Successive Discounts

When two discounts a% and b% are given successively, the Equivalent Single Discount is calculated as: (a + b − ab/100)%.

Marked Price and Selling Price

The Selling Price is the final amount paid by the customer after all discounts are subtracted from the Marked Price (List Price).

Question 74

If A means +, B means -, C means ×, D means ÷, then what will come in place of the question mark (?) in the following equation? 

21 D 3 B 4 C 5 A 22 = ?

  1. AOption (a)

    8

  2. BOption (b)

    9

  3. COption (c)

    7

  4. DOption (d)

    10

View answer & explanation

Correct answer

Answer: (b)B.

9

Why this answer is correct

Given Equation: 21 D 3 B 4 C 5 A 22 = ?

BODMAS Rule:

Decoding the given information:

AlphabetABCD
Meaning+-×÷

 

Now replacing the sign from left to right using BODMAS Rule, we get:

⇒ 21 ÷ 3 - 4 × 5 + 22

⇒ 7 - 20 + 22 = 9

Hence, the correct option is "Option 2".

Question 75

Refer to the given series and answer the question that follows (all numbers are single-digit numbers only, and all counting is to be done from left to right).

(Left) 2 2 4 8 2 4 6 4 2 6 8 8 6 7 4 5 3 6 2 8 7 1 3 3 6 8 6 4 (Right)

How many such odd digits are there, each of which is immediately preceded by a perfect square and immediately followed by an even digit?

(Note: I will be considered as a perfect square.)

  1. AOption (a)

    2

  2. BOption (b)

    1

  3. COption (c)

    4

  4. DOption (d)

    0

View answer & explanation

Correct answer

Answer: (d)D.

0

Why this answer is correct

Given series:

(Left) 2 2 4 8 2 4 6 4 2 6 8 8 6 7 4 5 3 6 2 8 7 1 3 3 6 8 6 4 (Right)

According to the question, such odd digits which are immediately preceded by perfect square and also immediately followed by an even digit:

Required condition:  perfect square - odd - Even

(Left) 2 2 4 8 2 4 6 4 2 6 8 8 6 7 4 5 3 6 2 8 7 1 3 3 6 8 6 4 (Right)

Thus, there is no such odd digits which are immediately preceded by perfect square and also immediately followed by an even digit.

Hence, "Option 4" is the correct answer.

Question 76

After fertilisation, which of the following develops a tough coat, is gradually converted into a seed and the zygote divides several times to form an embryo within it?

  1. AOption (a)

    Pistil

  2. BOption (b)

    Ovary

  3. COption (c)

    Gynoecium

  4. DOption (d)

    Ovule

View answer & explanation

Correct answer

Answer: (d)D.

Ovule

Why this answer is correct

The Correct answer is Ovule.

Key Points

  • After fertilisation, the ovule develops a tough outer coat known as the seed coat.
  • The ovule is gradually converted into a seed, which contains the embryo formed by the repeated division of the zygote.
  • The embryo is the future plant enclosed within the seed, surrounded by protective layers, aiding in its development under suitable conditions.
  • The ovule contains the female gametophyte, which is fertilised by the male gametes during reproduction.
  • Post fertilisation, the ovule undergoes changes such as the formation of the seed coat, storage of nutrients, and maturation into a functional seed.
  • This process is crucial for the reproductive success of flowering plants, ensuring the dispersal and germination of the next generation.

 Additional Information

  • Pistil
  • The pistil is the female reproductive organ of a flower, consisting of the stigma, style, and ovary.
  • Although it plays a role in reproduction, it is not directly converted into a seed.
  • The pistil facilitates the transfer of pollen to the ovary but does not form the embryo.
  • Ovary
  • The ovary is the part of the pistil that contains one or more ovules.
  • Post fertilisation, the ovary develops into a fruit, enclosing the seeds.
  • While important in reproduction, the ovary itself does not become the seed.
  • Gynoecium
  • The gynoecium refers collectively to the female reproductive structures in a flower, including pistils.
  • It is the overall organ system, not a specific part that develops into a seed.
  • Its primary function is to house and support fertilisation processes.

Question 77

The power input in a circuit P can be expressed in terms of voltage V and current I in the circuit as follows:

  1. AOption (a)

    P = VI

  2. BOption (b)

    P = V/I

  3. COption (c)

    P = V2I

  4. DOption (d)

    P = V2/I

View answer & explanation

Correct answer

Answer: (a)A.

P = VI

Why this answer is correct

The Correct answer is P = VI.

Key Points

  • The formula P = VI is the fundamental expression for calculating
  • in a circuit.
  • Power (P) in an electrical circuit represents the rate at which electrical energy is transferred or converted into another form of energy, such as heat or light.
  • The formula indicates that power is the product of voltage (V) and current (I), where:
  • Voltage (V) is the potential difference across two points in the circuit, measured in volts.
  • Current (I) is the flow of electric charge through a conductor, measured in amperes.
  • This formula is derived from the basic definition of power: Power = Work / Time. In the context of electricity, work is the product of charge and potential difference, and dividing it by time leads to the formula P = VI.
  • It is a widely used formula in analyzing electrical circuits, determining the efficiency of devices, and calculating energy consumption.
  • This relationship is valid for both direct current (DC) and alternating current (AC) circuits, though in AC circuits, factors such as phase difference and power factor may need to be considered.
  • For example, if the voltage across a circuit is 10 volts and the current is 2 amperes, the power is calculated as:
  • P = VI = 10 × 2 = 20 watts

 Additional Information

  • P = V/I
  • This formula is incorrect because dividing voltage by current gives resistance (R), not power.
  • The relationship is derived from Ohm's Law, which states that V = IR, where R is resistance.
  • P = V2I
  • This formula is incorrect and does not follow the principles of power calculation. It appears to be a misrepresentation of the power equation.
  • P = V2/I
  • This formula is also incorrect. It is not consistent with the physical laws governing electrical circuits.

Question 78

Based on the English alphabetical order, three of the following four letter-cluster pairs are alike in a certain way and thus form a group. Which pair does not belong to that group?

(Note: The odd one out is not based on the number of consonants/vowels or their position in the letter cluster.)

  1. AOption (a)

    SN-QU

  2. BOption (b)

    UP-SV

  3. COption (c)

    QL-OR

  4. DOption (d)

    OJ-MP

View answer & explanation

Correct answer

Answer: (a)A.

SN-QU

Why this answer is correct

Logic follows here is that the first letter is decreased by 5 and the second letter is increased by 3.

Option 1) SN-QU

Does not follow the same logic.

Option 2) UP-SV

Option 3) QL-OR

Option 4) OJ-MP

Hence the correct answer is "Option 1"

Question 79

SDFG is related to YJKM in a certain way based on the English alphabetical order. In the same way, QBZE is related to WHEK. To which of the following options is ITOW related, following the same logic? 

  1. AOption (a)

    OZTC

  2. BOption (b)

    MJVY

  3. COption (c)

    HBCT

  4. DOption (d)

    RYOM

View answer & explanation

Correct answer

Answer: (a)A.

OZTC

Why this answer is correct

Logic followed here is,

Given,

SDFG is related to YJKM

For, QBZE is related to WHEK

Similarly for ITOW is related to RYOM.

Hence the correct answer is "Option 1"

Question 80

Which of the following can increase the work done by a force on an object? 

  1. AOption (a)

    Reducing the mass. 

  2. BOption (b)

    Reducing the displacement. 

  3. COption (c)

    Reducing the force. 

  4. DOption (d)

    Increasing the displacement. 

View answer & explanation

Correct answer

Answer: (d)D.

Increasing the displacement. 

Why this answer is correct

The Correct answer is Increasing the displacement.

Key Points

  • The work done by a force on an object is calculated using the formula: Work = Force × Displacement × cos(θ), where θ is the angle between the force and displacement vectors.
  • Increasing the displacement directly increases the work done if the force and displacement are in the same direction (θ = 0 degrees).
  • The work done depends on the magnitude of the displacement, as a larger displacement under the same force results in higher work.
  • If the displacement increases while the force remains constant, the object moves farther, contributing to more work being done.
  • In physics, work is a measure of the energy transfer that occurs when an object is moved over a distance by an external force.
  • Thus, increasing the displacement is a practical way to enhance the work done, provided the force remains constant and is applied in the same direction.
  • This concept is widely applied in real-life scenarios, such as in machinery, where increasing the range of motion can yield higher energy output.

 Additional Information

  • Reducing the mass
  • Reducing the mass does not directly affect the work done, as work depends on force and displacement, not the mass of the object.
  • However, a lighter object requires less force to move, which can indirectly influence how much work is done under varying conditions.
  • Reducing the displacement
  • Reducing the displacement decreases the work done, as work is proportional to the magnitude of displacement.
  • This option is incorrect because it contradicts the principle of maximizing work by increasing displacement.
  • Reducing the force
  • Reducing the force also decreases the work done, as work is directly proportional to the applied force.
  • This option is incorrect because lowering the force reduces the energy transfer to the object, resulting in less work being done.

Question 81

Simplify the given expression.  

10 + 8 + 6 - 48 ÷ (4 × 6)

  1. AOption (a)

    12

  2. BOption (b)

    26

  3. COption (c)

    22

  4. DOption (d)

    -1

View answer & explanation

Correct answer

Answer: (c)C.

22

Why this answer is correct

Given:

10 + 8 + 6 − 48 ÷ (4 × 6)

Formula used:

BODMAS Rule (Bracket, Of, Division, Multiplication, Addition, Subtraction)

Calculations:

10 + 8 + 6 − 48 ÷ (4 × 6)

⇒ 10 + 8 + 6 − 48 ÷ 24

⇒ 10 + 8 + 6 − 2

⇒ 24 − 2

⇒ 22

∴ The correct answer is option (3).

Question 82

The average of Kanchan's marks in 7 subjects is 75. Her average in six subjects excluding Science is 72. How many marks did she get in Science? 

  1. AOption (a)

    93

  2. BOption (b)

    95

  3. COption (c)

    90

  4. DOption (d)

    72

View answer & explanation

Correct answer

Answer: (a)A.

93

Why this answer is correct

Shortcut Trick

Average marks of 7 subjects = 75

Average marks of 6 subjects = 72 (Decrease of 3 marks)

Science marks = Original Average + (Total subjects × Decrease in Average)

Science marks = 75 + (6 × 3) = 75 + 18 = 93

∴ The correct answer is 93.

Alternate Method

Given:

Number of subjects (n1) = 7, Average (A1) = 75

Number of subjects excluding Science (n2) = 6, Average (A2) = 72

Formula Used:

Total Marks = Average × Number of subjects

Marks in excluded subject = Total marks of all subjects − Total marks of remaining subjects

Calculations:

⇒ Total marks in 7 subjects = 7 × 75 = 525

⇒ Total marks in 6 subjects = 6 × 72 = 432

⇒ Marks in Science = 525 − 432

⇒ Marks in Science = 93

∴ The correct answer is 93.

Additional Information

Average Definition

Average is the sum of all observations divided by the total number of observations. Average = Sum ÷ Count.

Deviation Method

The sum of deviations of all items from their arithmetic mean is always zero. This can be used to find a missing value quickly.

Inclusion/Exclusion Rule

Value of excluded item = Old Sum − New Sum = (Old Count × Old Average) − (New Count × New Average).

Question 83

Evaluate the given expression. 

5 × 3 - 12 ÷ 4 + 8

  1. AOption (a)

    3

  2. BOption (b)

    20

  3. COption (c)

    14

  4. DOption (d)

    4

View answer & explanation

Correct answer

Answer: (b)B.

20

Why this answer is correct

Given:

Expression = 5 × 3 − 12 ÷ 4 + 8

Formula used:

BODMAS rule (Bracket, Of, Division, Multiplication, Addition, Subtraction)

Calculations:

5 × 3 − 12 ÷ 4 + 8

⇒ 5 × 3 − 3 + 8

⇒ 15 − 3 + 8

⇒ 23 − 3

⇒ 20

∴ The correct answer is option (2).

Question 84

Which of the following options should come in place of the question mark (?) in the given series based on the English alphabetical order?

MPL, ORN, QTP, SVR, ?

  1. AOption (a)

    UXT

  2. BOption (b)

    UTX

  3. COption (c)

    XTU

  4. DOption (d)

    XUT

View answer & explanation

Correct answer

Answer: (a)A.

UXT

Why this answer is correct

Given: MPL, ORN, QTP, SVR, ? 

Logic followed here is,

Hence the correct answer is "Option 1"

Question 85

When three parallel lines are cut by two transversals and the intercepts made by the first transversal are in the ratio 3 : 5, then the intercepts made by the second transversal are in the ratio ____

  1. AOption (a)

    9 : 25

  2. BOption (b)

    3 : 2

  3. COption (c)

    3 : 5

  4. DOption (d)

    1 : 1

View answer & explanation

Correct answer

Answer: (c)C.

3 : 5

Why this answer is correct

Shortcut Trick

By the Intercept Theorem (also known as Thales' Theorem for parallel lines), the ratio of intercepts made by any transversal on a set of parallel lines is always constant.

If the first transversal makes intercepts in the ratio 3 : 5, every other transversal will also make intercepts in the same ratio 3 : 5.

∴ The correct answer is 3 : 5.

Alternate Method

Given: Three parallel lines (say l1, l2, l3) and two transversals (say t1 and t2). The intercepts made by t1 are in ratio 3 : 5.

Formula Used: If three or more parallel lines are cut by two transversals, then the segments intercepted on the transversals are proportional.

⇒ Let the intercepts on the first transversal be A and B. Ratio A : B = 3 : 5.

⇒ Let the corresponding intercepts on the second transversal be C and D.

⇒ According to the proportionality theorem: A ÷ B = C ÷ D

⇒ 3 ÷ 5 = C ÷ D

⇒ C : D = 3 : 5

∴ The correct answer is 3 : 5.

Additional Information

Intercept Theorem

If three or more parallel lines intersect two transversals, then they cut off the transversals in proportional segments.

Midpoint Theorem

A special case of this theorem where the ratio is 1 : 1, implying the parallel line passes through the midpoints of the transversal segments.

Basic Proportionality Theorem (BPT)

Also known as Thales's Theorem, it states that if a line is drawn parallel to one side of a triangle to intersect the other two sides, the other two sides are divided in the same ratio.

Question 86

The danger signal lights are usually red in colour because red is:  

  1. AOption (a)

    not scattered at all by fog or smoke 

  2. BOption (b)

    highest reflected by fog or smoke 

  3. COption (c)

    least scattered by fog or smoke 

  4. DOption (d)

    highest scattered by fog or smoke 

View answer & explanation

Correct answer

Answer: (c)C.

least scattered by fog or smoke 

Why this answer is correct

The Correct answer is least scattered by fog or smoke.

Key Points

  • The red color of danger signals is chosen because it is least scattered by fog or smoke, ensuring that the signal is visible from a longer distance.
  • This phenomenon is explained by the concept of Rayleigh scattering, where the amount of scattering is inversely proportional to the fourth power of the wavelength.
  • Red light has the longest wavelength (approximately 620–750 nm) among the visible spectrum, making it less prone to scattering compared to other colors like blue or green.
  • Due to minimal scattering, red light travels farther through mediums like fog, smoke, and dust, making it ideal for use in emergency signals, traffic lights, and railway signals.
  • The choice of red ensures that warning signals are clear and effective even in adverse weather conditions, enhancing safety.

 Additional Information

  • Not scattered at all by fog or smoke
  • No light is completely unaffected by scattering in mediums like fog or smoke.
  • Even red light undergoes minimal scattering, but it is much less compared to shorter wavelengths like blue or violet.
  • Highest reflected by fog or smoke
  • This option is incorrect because reflection depends on surface properties, not the wavelength of light.
  • Red is least scattered, not primarily reflected, in fog or smoke.
  • Highest scattered by fog or smoke
  • Shorter wavelengths like blue and violet light are scattered more, which is why the sky appears blue.
  • Red light, having a longer wavelength, is least scattered, making this option incorrect.

Question 87

Two pipes C and D can fill a tank in 6 hours and 9 hours, respectively. They are opened alternately for | hour each, starting with C first. In what duration, will the tank be filled? 

  1. AOption (a)

    8 hours

  2. BOption (b)

    5 hours 

  3. COption (c)

    6 hours 

  4. DOption (d)

    7 hours 

View answer & explanation

Correct answer

Answer: (d)D.

7 hours 

Why this answer is correct

Shortcut Trick

LCM of 6 and 9 = 18 units (Total Work)

Efficiency of C = 18 ÷ 6 = 3 units/hour

Efficiency of D = 18 ÷ 9 = 2 units/hour

In 1 cycle (2 hours, alternating C then D), work done = 3 + 2 = 5 units

In 3 cycles (6 hours), work done = 5 × 3 = 15 units

Remaining work = 18 − 15 = 3 units, done by C on the 7th hour (taking exactly 1 hour)

Total time = 6 + 1 = 7 hours

∴ The correct answer is 7 hr.

Alternate Method

Given:

Time taken by pipe C = 6 hours

Time taken by pipe D = 9 hours

Formula Used:

Efficiency = Total Work ÷ Time

Calculations:

PersonDaysTotal WorkEfficiency
C6183
D92

First hour (C) work done = 3 units

Second hour (D) work done = 2 units

⇒ Total work done in 2 hours = 5 units

⇒ Work done in 6 hours = 5 × 3 = 15 units

⇒ Remaining work = 18 − 15 = 3 units

⇒ On the 7th hour, pipe C opens and does 3 units of work in 1 hour.

⇒ Total time taken = 6 + 1 = 7 hours

∴ The correct answer is 7 hr.

Additional Information

Alternate Day/Hour Work

In alternate work problems, group the work into cycles (e.g., 2-hour cycles). Find the work done per cycle, multiply to get as close to the total work as possible, and then handle the remaining work sequentially based on who starts first.

Pipes and Cisterns Efficiency

Inlet pipes have positive efficiency, whereas outlet or leak pipes have negative efficiency. Total capacity is determined by finding the LCM of individual times.

Question 88

1 kW power is equal to ______. (KW stands for kilowatt.)  

  1. AOption (a)

    1000 J/s

  2. BOption (b)

    10 J/s

  3. COption (c)

    100 J/s

  4. DOption (d)

    1 J/s

View answer & explanation

Correct answer

Answer: (a)A.

1000 J/s

Why this answer is correct

The Correct answer is 1 kW = 1000 J/s.

Key Points

  • The unit kilowatt (kW) is a measure of power in the International System of Units (SI).
  • 1 kilowatt is equivalent to 1000 watts (W), where 1 watt is defined as 1 joule per second (1 W = 1 J/s).
  • Thus, 1 kW = 1000 J/s, which means that 1 kilowatt represents the transfer of 1000 joules of energy per second.
  • This relationship is derived from the basic definition of power, which is the rate of doing work or transferring energy.
  • The unit kilowatt is commonly used in various applications, including electricity billing, mechanical systems, and energy consumption measurements.
  • For example, the power rating of household appliances like air conditioners, heaters, and washing machines is often given in kilowatts.
  • This conversion is fundamental in understanding the energy consumption and efficiency of devices, making it essential for calculations in physics and engineering.

 Additional Information

  • 10 J/s
  • This is a smaller unit of power and does not equate to 1 kilowatt. It is equivalent to 10 watts, which is significantly less than 1 kW.
  • 100 J/s
  • While closer in value, this is still much smaller than 1 kilowatt. It represents 100 watts, which is one-tenth of a kilowatt.
  • 1 J/s
  • This is the definition of 1 watt, the basic unit of power in the SI system. However, it is far smaller than 1 kilowatt, as it is only one-thousandth of a kilowatt.

Question 89

The term ‘Catenation’ is used to define a unique property of carbon. Which of the following gives the correct definition of catenation?  

  1. AOption (a)

    Unique ability to form bonds with other atoms of carbon. 

  2. BOption (b)

    Unique ability to form bonds with other atoms of hydrogen. 

  3. COption (c)

    Unique ability to form bonds with other atoms of nitrogen. 

  4. DOption (d)

    Unique ability to form bonds with other atoms of oxygen.  

View answer & explanation

Correct answer

Answer: (a)A.

Unique ability to form bonds with other atoms of carbon. 

Why this answer is correct

The Correct answer is Unique ability to form bonds with other atoms of carbon.

Key Points

  • Catenation is the property by which carbon atoms form strong covalent bonds with other carbon atoms to produce long chains, branched structures, or rings.
  • This unique property arises due to the small size of carbon and the strength of the carbon-carbon bond, which is stronger than bonds formed by most other elements with themselves.
  • Carbon exhibits this property more prominently than other elements because of its ability to form single, double, and triple covalent bonds with itself.
  • Catenation allows carbon to form a vast number of compounds, making it the basis of organic chemistry and life.
  • Examples of compounds formed due to catenation include hydrocarbons (alkanes, alkenes, alkynes), as well as more complex molecules like proteins, carbohydrates, and DNA.
  • This property also explains the diversity of carbon compounds, which is unmatched by any other element in the periodic table.

 Additional Information

  • Unique ability to form bonds with other atoms of hydrogen
  • Hydrogen bonds with carbon to form hydrocarbons, but this does not define the property of catenation.
  • Hydrocarbons like methane (CH₄) are formed due to the bonding between carbon and hydrogen, but this is not specific to the unique bonding of carbon with itself.
  • Unique ability to form bonds with other atoms of nitrogen
  • Nitrogen can form bonds with carbon in amino acids and other organic molecules, but it does not exhibit the extensive catenation property like carbon.
  • Nitrogen primarily forms triple bonds in diatomic nitrogen (N₂), which is stable but unrelated to carbon's catenation.
  • Unique ability to form bonds with other atoms of oxygen
  • Oxygen forms bonds with carbon in functional groups like alcohols (-OH), carboxylic acids (-COOH), and ketones (>C=O).
  • However, oxygen does not form long chains or networks by bonding with itself, unlike carbon.

Question 90

Swarna runs at a speed of 10 km/h. How long will she take to cover 200 m?  

  1. AOption (a)

    120 seconds 

  2. BOption (b)

    90 seconds 

  3. COption (c)

    72 seconds 

  4. DOption (d)

    54 seconds 

View answer & explanation

Correct answer

Answer: (c)C.

72 seconds 

Why this answer is correct

Shortcut Trick

Convert speed from km/h to m/s by multiplying with 5/18.

Speed = 10 × (5/18) = 25/9 m/s.

Time = Distance ÷ Speed = 200 ÷ (25/9) = 200 × 9 ÷ 25 = 8 × 9 = 72 sec.

∴ The correct answer is 72 sec.

Alternate Method

Given:

Speed of Swarna = 10 km/h

Distance to cover = 200 m

Formula Used:

Time = Distance ÷ Speed

Conversion: 1 km/h = 5/18 m/s

Calculations:

⇒ Speed in m/s = 10 × (5/18) m/s

⇒ Speed = 50/18 = 25/9 m/s

⇒ Time = 200 ÷ (25/9)

⇒ Time = 200 × (9/25)

⇒ Time = 8 × 9

⇒ Time = 72 sec

∴ The correct answer is 72 sec.

Additional Information

Unit Conversion

To convert km/h to m/s, multiply by 5/18. To convert m/s to km/h, multiply by 18/5.

Speed-Distance Relationship

Distance = Speed × Time. When distance is constant, speed is inversely proportional to time.

Average Speed

Average Speed = Total Distance ÷ Total Time. For two equal distances with speeds x and y, Average Speed = 2xy/(x+y).

Question 91

Nayab Singh Saini was appointed the Chief Minister of _____ in October 2024. 

  1. AOption (a)

    Himachal Pradesh

  2. BOption (b)

    Jharkhand

  3. COption (c)

    Haryana

  4. DOption (d)

    Punjab

View answer & explanation

Correct answer

Answer: (c)C.

Haryana

Why this answer is correct

The Correct answer is Haryana.

Key Points

  • Nayab Singh Saini was appointed as the Chief Minister of Haryana in October 2024.
  • Haryana is a state located in northern India and is known for its rich history and significance in Indian culture.
  • The state was carved out from the former Punjab state on 1 November 1966 on a linguistic basis.
  • Haryana is a major agricultural state and is often referred to as the "Green Land of India" due to its contribution to the country's food grain production.
  • The state is also known for its significant role in the Indian freedom struggle and for being the site of the historic Battle of Panipat.
  • Nayab Singh Saini is a prominent political leader known for his contributions to the state's development and governance.
  • Haryana has a robust industrial base, with sectors such as automobile manufacturing, IT services, and education contributing to its economy.

 Additional Information

  • Himachal Pradesh
  • Himachal Pradesh is a state in northern India known for its Himalayan landscapes and hill stations.
  • Its capital is Shimla, which is a popular tourist destination.
  • The state is famous for its apple orchards and trekking routes.
  • The region is also known for its contribution to hydroelectric power generation in India.
  • Jharkhand
  • Jharkhand is a state in eastern India known for its mineral wealth, especially coal and iron ore.
  • The state is rich in natural resources and has a significant tribal population.
  • It is home to prominent industrial hubs like Jamshedpur and Bokaro Steel City.
  • Punjab
  • Punjab is a state in northern India and is often referred to as the "Granary of India" due to its high agricultural productivity.
  • The state is known for its rich cultural heritage and is the birthplace of Sikhism.
  • Its capital is Chandigarh, which is also a union territory and serves as the capital of Haryana.

Question 92

Identify the INCORRECT statement about muscle tissue. 

  1. AOption (a)

    The limbs have voluntary muscles. 

  2. BOption (b)

    Muscle tissues are made up of cuboidal cells. 

  3. COption (c)

    Microscopes reveal alternate light and dark bands in voluntary muscles.  

  4. DOption (d)

    Special contractile proteins are present in muscles. 

View answer & explanation

Correct answer

Answer: (b)B.

Muscle tissues are made up of cuboidal cells. 

Why this answer is correct

The Correct answer is Muscle tissues are made up of cuboidal cells.

Key Points

  • Muscle tissues are not made up of cuboidal cells. Instead, they are composed of specialized elongated cells called muscle fibers, which are designed for contraction and movement.
  • Cuboidal cells are epithelial cells, typically found in glands and ducts, where their primary function is secretion or absorption, not contraction.
  • Muscle tissue is categorized into three types: skeletal, smooth, and cardiac muscle, all of which have unique structural and functional features.
  • Skeletal muscle fibers are long, cylindrical, and multinucleated, with alternating light and dark bands, indicating their striated nature.
  • Contractile proteins, such as actin and myosin, are present in all muscle tissues and are responsible for the contraction and relaxation process.
  • Muscle tissues are integral to various bodily functions, including movement, posture maintenance, and internal organ functioning like the heart and digestive system.

 Additional Information

  • The limbs have voluntary muscles
  • Voluntary muscles, also known as skeletal muscles, are under conscious control and are responsible for movements of the limbs and body.
  • These muscles are connected to bones via tendons and work in pairs to perform movements like flexion and extension.
  • Microscopes reveal alternate light and dark bands in voluntary muscles
  • Skeletal muscles are striated, meaning they have alternating light (I-bands) and dark (A-bands) bands visible under a microscope, which are due to the arrangement of actin and myosin filaments.
  • This striation is a key feature distinguishing skeletal muscles from smooth muscles, which lack this pattern.
  • Special contractile proteins are present in muscles
  • Muscles contain specialized contractile proteins such as actin and myosin, which interact to produce contraction and generate force.
  • Other associated proteins, like tropomyosin and troponin, help regulate the contraction process.

Question 93

Which of the following banks launched a special debit card for visually impaired customers in October 2024?

  1. AOption (a)

    HDFC Bank

  2. BOption (b)

    State Bank of India

  3. COption (c)

    Punjab National Bank

  4. DOption (d)

    Canara Bank 

View answer & explanation

Correct answer

Answer: (c)C.

Punjab National Bank

Why this answer is correct

The Correct answer is Punjab National Bank.

Key Points

  • Punjab National Bank (PNB) launched a special debit card for visually impaired customers in October 2024.
  • This initiative aims to promote financial inclusion and make banking services more accessible to individuals with visual impairments.
  • The debit card is designed with Braille features to help visually impaired users recognize and operate it independently.
  • It allows visually impaired customers to conduct secure transactions such as cash withdrawals, balance inquiries, and purchases.
  • The move aligns with PNB’s commitment to empowering people with disabilities and catering to their specific banking needs.
  • PNB is one of the leading public sector banks in India, with a history of implementing customer-focused solutions.
  • This innovative debit card is part of the bank's efforts to comply with the Rights of Persons with Disabilities Act, 2016, which emphasizes equal access to services for people with disabilities.

 Additional Information

  • HDFC Bank
  • HDFC Bank is one of the largest private sector banks in India.
  • It is known for offering a wide range of digital banking products and innovative financial services.
  • HDFC Bank focuses on enhancing digital accessibility but has not specifically launched a debit card for visually impaired customers.
  • State Bank of India (SBI)
  • SBI is the largest public sector bank in India and provides financial services to a vast customer base.
  • SBI has a history of introducing specialized products, such as loans for women and farmers, but it has not launched a debit card exclusively for visually impaired customers.
  • Canara Bank
  • Canara Bank is another major public sector bank in India.
  • It offers a variety of banking products and services, including debit and credit cards, but there is no record of it introducing a debit card specifically for visually impaired customers.

Question 94

Gautam starts from Point A and drives 30 km towards South. He then takes a left turn, drives 15 km, turns left and drives 42 km. He then takes a left turn and drives 7 km. He takes a final left turn, drives 12 km and stops at Point P. How far (shortest distance) and towards which direction should he drive in order to reach Point A again?

(All turns are 90 degree turns only unless otherwise specified.)

  1. AOption (a)

    10 km towards East  

  2. BOption (b)

    5 km towards West 

  3. COption (c)

    10 km towards West  

  4. DOption (d)

    8 km towards West 

View answer & explanation

Correct answer

Answer: (d)D.

8 km towards West 

Why this answer is correct

Given, 

Gautam starts from Point A and drives 30 km towards South.

He then takes a left turn, drives 15 km, turns left and drives 42 km.

He then takes a left turn and drives 7 km.

He takes a final left turn, drives 12 km and stops at Point P.

He should drive 8 km in the West direction in order to reach Point A again.

Hence the correct answer is "Option 4"

Question 95

The simplified value of 1.0816\sqrt{1.0816} is:

  1. AOption (a)

    1.35

  2. BOption (b)

    1.04

  3. COption (c)

    0.904

  4. DOption (d)

    1.286

View answer & explanation

Correct answer

Answer: (b)B.

1.04

Why this answer is correct

Shortcut Trick

Observe the last digit of 1.0816, which is 6. The square root must end in 4 or 6.

Since 12 = 1 and 1.12 = 1.21, the value 1.0816 lies between them, closer to 1.

Check 1.04: 1042 = (100 + 4)2 = 10000 + 16 + 800 = 10816.

Adjusting decimals: √1.0816 = 1.04.

∴ The correct answer is 1.04.

Alternate Method

Given: Value = √1.0816

Method: Fraction Conversion and Square Root

⇒ √1.0816 = √(10816 ÷ 10000)

⇒ √10816 ÷ √10000

⇒ Factorizing 10816: 10816 = 26 × 132

⇒ √10816 = 23 × 13 = 8 × 13 = 104

⇒ √10000 = 100

⇒ Result = 104 ÷ 100 = 1.04

∴ The correct answer is 1.04.

Additional Information

Square Root of Decimals

When finding the square root of a decimal, the number of decimal places in the result is half the number of decimal places in the original number.

Perfect Square Ending Digits

A perfect square ending in 6 will have a square root ending in either 4 or 6. If it ends in 5, the root ends in 5.

Long Division Method

For non-obvious numbers, use the long division method by grouping digits in pairs starting from the decimal point.

Question 96

What is the SI unit of universal gravitational constant G?

  1. AOption (a)

    N m2 / kg-1

  2. BOption (b)

    N kgm2

  3. COption (c)

    N m2 / kgs-1

  4. DOption (d)

    N m2 / kg2

View answer & explanation

Correct answer

Answer: (d)D.

N m2 / kg2

Why this answer is correct

The Correct answer is N m2 / kg2.

Key Points

  • The universal gravitational constant (G) is a fundamental physical constant that appears in Newton's law of universal gravitation.
  • Its value is approximately 6.674 × 10-11 N m2 / kg2.
  • The SI unit of G is derived from the formula of gravitational force: F = G (m1m2) / r2, where:
  • F is the force measured in newtons (N).
  • m1 and m2 are masses measured in kilograms (kg).
  • r is the distance between the two masses measured in meters (m).
  • From the formula, the unit of G is derived as N m2 / kg2.
  • G is a crucial constant for calculating the gravitational attraction between two objects.
  • This constant is used in various fields, including astrophysics, geophysics, and space exploration.

 Additional Information

  • N m2 / kg-1
  • This unit is incorrect as the exponent of kg should be -2 instead of -1.
  • The term does not align with Newton's law of universal gravitation and is mathematically incorrect.
  • N kg m2
  • This unit is incorrect because G measures a force-related constant, and the unit does not account for the gravitational relationship between masses.
  • The term does not include the inverse square relationship of distance.
  • N m2 / kg s-1
  • This unit is incorrect as it includes seconds (s), which is irrelevant to the concept of gravitational force.
  • G does not involve time in its calculations, hence this unit is invalid.

Question 97

Where should the object be placed around the concave mirror to ensure that the size of the image is the same as the size of the object? 

  1. AOption (a)

    Between focus F and centre of curvature C 

  2. BOption (b)

    At focus F 

  3. COption (c)

    At C, centre of curvature  

  4. DOption (d)

    Between focus F and pole P 

View answer & explanation

Correct answer

Answer: (c)C.

At C, centre of curvature  

Why this answer is correct

The correct answer is At C, centre of curvature.

Key Points

  • When an object is placed at the centre of curvature (C) of a concave mirror, the image formed is of the same size as the object.
  • The image formed in this case is real, inverted, and located at the centre of curvature itself (C).
  • This happens because at the centre of curvature, the object and its image are equidistant from the mirror, and the curvature of the mirror ensures that light rays converge perfectly to form an image of the same size.
  • The laws of reflection explain this phenomenon, where the angle of incidence equals the angle of reflection.
  • This property of concave mirrors is used in various optical instruments like reflecting telescopes and shaving mirrors where magnification or clarity is required at specific distances.
  • For practical purposes, this placement is crucial in understanding the behavior of light and the principles of image formation.

 Additional Information

  • Between focus F and centre of curvature C
  • When the object is placed between the focus (F) and the centre of curvature (C), the image formed is real, inverted, and larger than the object.
  • This is a characteristic property of concave mirrors where magnification increases as the object approaches the focus.
  • At focus F
  • When the object is placed at the focus (F), the reflected rays become parallel, and the image is formed at infinity.
  • The image in this case is highly magnified, real, and inverted.
  • Between focus F and pole P
  • If the object is placed between the focus (F) and the pole (P), the image formed is virtual, erect, and magnified.
  • This property is used in applications such as makeup mirrors or dentist’s mirrors.

Question 98

Two numbers are less than a third number by 30% and 37%, respectively. By what percentage is the second number less than the first? 

  1. AOption (a)

    8%

  2. BOption (b)

    10%

  3. COption (c)

    12%

  4. DOption (d)

    15%

View answer & explanation

Correct answer

Answer: (b)B.

10%

Why this answer is correct

Shortcut Trick

Let the third number be 100.

First number = 100 − 30 = 70.

Second number = 100 − 37 = 63.

Difference = 70 − 63 = 7.

Required percentage = (Difference ÷ First number) × 100 = (7 ÷ 70) × 100 = 10%.

∴ The correct answer is 10%.

Alternate Method

Given:

Let the third number (N3) = 100.

First number (N1) = N3 − 30% of N3

⇒ N1 = 100 − 30 = 70

Second number (N2) = N3 − 37% of N3

⇒ N2 = 100 − 37 = 63

Calculations:

Difference between N1 and N2 = 70 − 63 = 7

Percentage by which N2 is less than N1 = (Difference ÷ N1) × 100

⇒ Required Percentage = (7 ÷ 70) × 100

⇒ Required Percentage = 1/10 × 100 = 10%

∴ The correct answer is 10%.

Additional Information

Percentage Comparison

When comparing two values A and B, the percentage by which B is less than A is given by [(A − B) ÷ A] × 100.

Base Value Selection

In comparative problems, the value following 'than' or 'to' is usually taken as the base (denominator) for percentage calculations.

Question 99

The cause of being the refractive index(u) of transparent medium > 1, is: 

  1. AOption (a)

    Speed of light in vacuum < speed of light in transparent medium 

  2. BOption (b)

    Wavelength of light gets change as it moves from denser to rarer medium 

  3. COption (c)

    Speed of light in vacuum > speed of light in transparent medium 

  4. DOption (d)

    Speed of light in vacuum = speed of light in transparent medium  

View answer & explanation

Correct answer

Answer: (c)C.

Speed of light in vacuum > speed of light in transparent medium 

Why this answer is correct

The Correct answer is Speed of light in vacuum > speed of light in transparent medium.

Key Points

  • The refractive index (denoted as μ) of a medium is defined as the ratio of the speed of light in a vacuum (c) to the speed of light in that medium (v).
  • The formula is: μ = c/v.
  • Since the speed of light in a vacuum is always greater than its speed in any transparent medium, the refractive index is always greater than 1.
  • The refractive index indicates how much the light bends when it enters a medium from another medium (such as air to glass).
  • A higher refractive index implies that the medium is optically denser, causing light to slow down more significantly.
  • This phenomenon occurs because light interacts with the particles in the medium, which affects its propagation speed.
  • Examples of materials with a high refractive index include diamond (μ ≈ 2.42) and glass (μ ≈ 1.5).

 Additional Information

  • Speed of light in vacuum = speed of light in transparent medium
  • This option is incorrect as the speed of light in a vacuum is the universal constant (c ≈ 3 × 108 m/s) and is always faster than its speed in any other medium.
  • In any transparent medium like water, glass, or diamond, light slows down due to interactions with the medium's particles.
  • Speed of light in vacuum < speed of light in transparent medium
  • This option is also incorrect because light cannot travel faster in any medium than it does in a vacuum.
  • The vacuum is the medium with the least optical density, allowing light to travel at its maximum speed.
  • Wavelength of light gets change as it moves from denser to rarer medium
  • While the wavelength of light does change when it moves between media of different refractive indices, this is not the direct cause of the refractive index being greater than 1.
  • The change in wavelength is a result of the speed of light changing, which is explained by the refractive index.

Question 100

In a parallelogram two adjacent sides are in the ratio 2 : 3 and the perimeter is 60 cm. The length of each of the two shorter sides of this parallelogram is: 

  1. AOption (a)

    18 cm

  2. BOption (b)

    13 cm

  3. COption (c)

    19 cm

  4. DOption (d)

    12 cm

View answer & explanation

Correct answer

Answer: (d)D.

12 cm

Why this answer is correct

Shortcut Trick

Sum of ratio parts for adjacent sides = 2 + 3 = 5 units.

Semi-perimeter of the parallelogram = 60 ÷ 2 = 30 cm.

Total units (5) = 30 cm ⇒ 1 unit = 30 ÷ 5 = 6 cm.

Length of shorter side = 2 units × 6 = 12 cm.

∴ The correct answer is 12 cm.

Alternate Method

Given:

Ratio of adjacent sides = 2 : 3

Perimeter of the parallelogram = 60 cm

Formula Used:

Perimeter of a parallelogram = 2 × (Sum of adjacent sides)

Calculations:

⇒ Let the length of the shorter side be 2x and the longer side be 3x.

⇒ Perimeter = 2 × (2x + 3x) = 60

⇒ 2 × 5x = 60

⇒ 10x = 60

⇒ x = 60 ÷ 10 = 6

⇒ Shorter side = 2x = 2 × 6 = 12 cm.

⇒ Longer side = 3x = 3 × 6 = 18 cm.

The length of each of the two shorter sides is 12 cm, which corresponds to Option (4).

∴ The correct answer is 12 cm.

Additional Information

Properties of a Parallelogram

Opposite sides are equal and parallel. Opposite angles are equal, and diagonals bisect each other.

Area of Parallelogram

Area = base × height. Alternatively, Area = a × b × sin(θ), where a and b are adjacent sides and θ is the included angle.

Perimeter vs Area

Perimeter is the total boundary length 2(a+b), while Area is the space enclosed within the boundary.

100 questions in the full paper