Search Previous Year Questions

The correct answer is Change in temperature.

Key Points

• A change in temperature is one of the most common indications that a chemical reaction has occurred. It signifies that energy has either been released (exothermic reaction) or absorbed (endothermic reaction).
• In chemical reactions, the formation of new substances involves breaking and forming chemical bonds, which often involves an exchange of energy in the form of heat. This is observed as a change in temperature.
• For example, when quicklime (calcium oxide) reacts with water, it produces calcium hydroxide and releases heat, causing the mixture to become hot. This is an exothermic reaction.
• Similarly, in endothermic reactions, such as the decomposition of calcium carbonate into calcium oxide and carbon dioxide, heat is absorbed, and the surroundings may feel cooler.
• Other changes such as a change in texture, size, or shape are generally physical changes and do not confirm the occurrence of a chemical reaction. Hence, option 4 is correct.

Additional Information

• Indicators of a chemical reaction:
• Change in color: Some chemical reactions result in a noticeable change in color. For example, when iron rusts, it changes from a metallic gray to a reddish-brown color due to the formation of iron oxide.
• Evolution of gas: The formation of gas bubbles during a reaction, such as in the reaction between vinegar (acetic acid) and baking soda (sodium bicarbonate), indicates a chemical reaction.
• Precipitate formation: A precipitate is a solid that forms from a solution during a chemical reaction. For instance, when solutions of silver nitrate and sodium chloride are mixed, silver chloride precipitates out.
• Change in smell: A new odor may be produced during a chemical reaction, such as when food spoils or burns.
• Emission of light: Some reactions release energy in the form of light, such as the combustion of magnesium ribbon, which produces a bright white flame.
• Physical changes vs. chemical changes:
• Physical changes involve changes in the physical state or appearance of a substance without altering its chemical composition. Examples include melting, freezing, and breaking.
• Chemical changes result in the formation of new substances with different chemical properties. Examples include rusting, combustion, and digestion.
• Examples of exothermic and endothermic reactions:
• Exothermic reactions: Combustion of fuels, neutralization reactions between acids and bases, and the condensation of water vapor.
• Endothermic reactions: Photosynthesis, melting of ice, and evaporation of water.
• Applications of temperature change in chemical reactions:
• In industries, exothermic reactions are used for heat generation, such as in combustion engines.
• Endothermic reactions are exploited in cooling applications, such as instant cold packs used in sports injuries.
• Monitoring temperature changes in reactions can help chemists understand reaction kinetics and optimize processes.

Important Points

• Exothermic reactions: Reactions where heat is released into the surroundings, often causing a rise in temperature.
• Endothermic reactions: Reactions that absorb heat from the surroundings, causing a drop in temperature.
• Chemical energy: The energy stored in the chemical bonds of substances, which is either released or absorbed during a reaction.
• Examples in daily life: Cooking food involves endothermic reactions, while burning wood in a fireplace is an example of an exothermic reaction.

The correct answer is Tibeto-Burman.

Key Points

• The Tibeto-Burman languages are predominantly spoken by communities residing in the Himalayan belt of India, which is contiguous with international boundaries like China, Bhutan, Nepal, and Myanmar.
• These languages are primarily spoken in regions such as Arunachal Pradesh, Sikkim, Ladakh, Himachal Pradesh, Uttarakhand, Meghalaya, Nagaland, and Manipur.
• The Tibeto-Burman languages belong to the larger Sino-Tibetan language family, which is one of the world's major language families.
• Communities speaking these languages are often ethnic minorities with distinct cultural and linguistic identities, many of which are influenced by their proximity to neighboring Himalayan countries.
• Some prominent examples of Tibeto-Burman languages include Bodo, Lepcha, Meitei (Manipuri), Garo, and Naga languages.

Additional Information

• Indo-Aryan Languages:
• The Indo-Aryan languages are a branch of the Indo-European language family and are the most widely spoken language group in India.
• They include major languages such as Hindi, Bengali, Punjabi, Marathi, Gujarati, and Odia, primarily spoken in the northern, central, and western parts of India.
• Unlike Tibeto-Burman languages, Indo-Aryan languages are not confined to the Himalayan belt.
• Dravidian Languages:
• Dravidian languages are primarily spoken in southern India and include prominent languages such as Telugu, Tamil, Kannada, and Malayalam.
• They are not geographically connected to the Himalayan region, as they are mainly centered in the Deccan Plateau.
• Austric Languages:
• Austric or Austroasiatic languages are spoken by tribal communities in eastern and central India, such as the Santhals, Mundas, and Khasis.
• These languages are primarily found in regions like Jharkhand, Chhattisgarh, Odisha, and the Northeastern states, but they are not concentrated in the Himalayan belt.
• Key Features of Tibeto-Burman Languages:
• The Tibeto-Burman languages are tonal, meaning the meaning of a word can change based on the pitch or tone used while pronouncing it.
• They have rich oral traditions, and many languages lack a written script, relying on oral storytelling and folklore.
• These languages are often influenced by the cultural and political interactions with Tibetan, Chinese, and Southeast Asian cultures.

Important Points

• Historical Context:
• The Tibeto-Burman language family has ancient roots and has been present in the Himalayan region for thousands of years.
• Migration patterns from Tibet and Southeast Asia significantly shaped the linguistic landscape of the region.
• Preservation Efforts:
• Many Tibeto-Burman languages are endangered due to the dominance of larger languages like Hindi and English, leading to a decline in native speakers.
• Efforts by government and cultural organizations are underway to document and preserve these languages.

The correct answer is Odisha.

Key Points

• The Balimela Power Plant is located in the state of Odisha, India. It is a hydroelectric power plant that significantly contributes to the power supply in the region.
• The project is built on the Sileru River, which is a tributary of the Godavari River, and is situated in the Malkangiri district of Odisha.
• This hydroelectric project was developed jointly by the states of Odisha and Andhra Pradesh, showcasing interstate collaboration in power generation.
• The Balimela Dam, which is an integral part of this project, is a multipurpose dam designed for both irrigation and power generation purposes. It has helped in improving agricultural productivity in the region.
• The hydroelectric power station has an installed capacity of 510 MW, consisting of multiple turbine units to generate electricity efficiently.

Additional Information

• Location and Geography:
• The Balimela Power Plant is located in the Malkangiri district of Odisha, which is known for its rich natural resources and hilly terrain.
• The Sileru River, where the dam is constructed, flows through picturesque landscapes and provides the necessary water resources for the power plant.
• Hydroelectric Power in India:
• India has several hydroelectric power plants, which play a crucial role in the country's energy mix. Hydropower is a renewable and eco-friendly source of energy.
• Odisha is home to several hydroelectric projects, including the Hirakud Dam, Indravati Power Plant, and Upper Kolab Project.
• Interstate Collaboration:
• The Balimela project is an example of interstate collaboration between Odisha and Andhra Pradesh for efficient resource utilization and power generation.
• This collaboration highlights the importance of cooperative federalism in India’s infrastructure development.
• Energy Contribution:
• The Balimela Power Plant contributes significantly to the energy needs of both Odisha and Andhra Pradesh, ensuring reliable electricity supply to various sectors.
• It supports industrial development and rural electrification in the region.
• Environmental and Socioeconomic Impact:
• The project has had a positive impact on agriculture through improved irrigation facilities.
• It has also created employment opportunities during its construction and operational phases.

Important Points

• Hydropower Potential in India:
• India is the 7^th largest producer of hydropower in the world, with an estimated potential of about 145,320 MW.
• Major river systems such as the Ganga, Brahmaputra, and Godavari provide significant hydropower opportunities.
• Significance of Balimela Power Plant:
• It has played a vital role in stabilizing the power grid in eastern India and supporting regional energy demands.
• The project is a part of Odisha's broader strategy to harness its water resources for sustainable development.
• Challenges in Hydropower Projects:
• Environmental concerns, such as deforestation and displacement of local communities, often pose challenges to hydropower projects.
• Proper planning and implementation are necessary to balance development and conservation.

Shortcut Trick

Convert all bases directly to 3 to simplify.

⇒ 3⁵ − 3⁵ + √[(3³⁶ + 3²⁶) ÷ (3¹⁸ + 3²⁸)]

⇒ 0 + √[{3²⁶(3¹⁰ + 1)} ÷ {3¹⁸(1 + 3¹⁰)}]

⇒ √(3⁸) = 3⁴ = 81

∴ The correct answer is 81.

Alternate Method

Given:

3⁵ − (1/3)⁻⁵ + √[(27¹² + 9¹³) ÷ (27⁶ + 9¹⁴)]

Formulas Used:

⇒ (a^m)ⁿ = a^mn

⇒ a^m ÷ aⁿ = a^m−n

⇒ a^−m = 1 ÷ a^m

Calculations:

⇒ First, evaluate the first two terms:

⇒ (1/3)⁻⁵ = (3⁻¹)⁻⁵ = 3⁵

⇒ 3⁵ − 3⁵ = 0

⇒ Second, evaluate the fraction inside the square root by converting bases to 3:

⇒ Numerator: 27¹² + 9¹³ = (3³)¹² + (3²)¹³ = 3³⁶ + 3²⁶

⇒ Denominator: 27⁶ + 9¹⁴ = (3³)⁶ + (3²)¹⁴ = 3¹⁸ + 3²⁸

⇒ Take out the common minimum powers from numerator and denominator:

⇒ Fraction = [3²⁶(3¹⁰ + 1)] ÷ [3¹⁸(1 + 3¹⁰)]

⇒ Cancel out the common term (3¹⁰ + 1):

⇒ Fraction = 3²⁶ ÷ 3¹⁸

⇒ Fraction = 3²⁶⁻¹⁸ = 3⁸

⇒ Finally, substitute back into the full expression:

⇒ 0 + √(3⁸)

⇒ 3⁴ = 81

∴ The correct answer is 81.

Additional Information

Laws of Exponents (Multiplication & Division)

When multiplying terms with the same base, add their powers: a^m × aⁿ = a^m+n. When dividing, subtract the powers: a^m ÷ aⁿ = a^m−n.

Negative Exponents

A negative exponent indicates the reciprocal of the base raised to the positive power: a^−m = 1 ÷ a^m or (a/b)^−m = (b/a)^m.

Power of a Power Rule

When raising a power to another power, multiply the exponents: (a^m)ⁿ = a^mn. This is especially useful for converting composite bases to prime bases.

Fractional Exponents and Roots

The square root of a term can be written as a fractional exponent: √a = a^1/2. Therefore, √(a^m) = a^m/2.

Shortcut Trick

If A and B together take 'x' days and B alone takes 'y' days, A alone will take (x × y) ÷ (y − x) days.

Here, x = 10 days and y = 15 days.

Time taken by A = (10 × 15) ÷ (15 − 10)

Time taken by A = 150 ÷ 5 = 30 days.

∴ The correct answer is 30 days.

Alternate Method

Given:

Time taken by A and B together = 10 days

Time taken by B alone = 15 days

Calculations:

⇒ Efficiency of A = Efficiency of (A + B) − Efficiency of B

⇒ Efficiency of A = 3 − 2 = 1 unit/day

⇒ Time taken by A alone = Total Work ÷ Efficiency of A

⇒ Time taken by A alone = 30 ÷ 1 = 30 days

∴ The correct answer is 30 days.

Additional Information

Pipes and Cisterns

This topic follows the exact same LCM efficiency method. An inlet pipe has positive efficiency (+), while a leak or outlet pipe has negative efficiency (−).

Work and Wages

Total wages are distributed strictly in proportion to the total work done by each individual. If they work for the same number of days, wages are divided directly in the ratio of their efficiencies.

Alternate Days Work

Group the work into 2-day cycles (if two people are working alternately) and find the cycle's combined efficiency. Then divide the total work by this to find the number of complete cycles.

Shortcut Trick

Expand the expression directly using the distributive property:

⇒ 5x² − 5x + 7x² − 14 + 15

Combine the like terms:

⇒ 12x² − 5x + 1

∴ The correct answer is 12x² − 5x + 1.

Alternate Method

Given:

Expression: x(5x − 5) + 7(x² − 2) + 15

Calculations:

Multiply the terms outside the brackets with the terms inside:

⇒ (x × 5x) − (x × 5) + (7 × x²) − (7 × 2) + 15

⇒ 5x² − 5x + 7x² − 14 + 15

Group the x² terms, x terms, and constant values together:

⇒ (5x² + 7x²) − 5x + (15 − 14)

Add the coefficients of the like terms:

⇒ 12x² − 5x + 1

∴ The correct answer is 12x² − 5x + 1.

Additional Information

Distributive Property

The distributive property states that multiplying a sum by a number gives the same result as multiplying each addend by the number. Rule: a(b + c) = ab + ac.

Combining Like Terms

Like terms are terms that contain the same variables raised to the exact same powers. They can be simplified by adding or subtracting their numerical coefficients.

BODMAS Rule

BODMAS stands for Brackets, Orders, Division / Multiplication, and Addition / Subtraction. It sets the strict order of operations for solving any mathematical expression.

Shortcut Trick

The options are provided in decimal form (ratio) instead of standard percentage format.

Required decimal = A's score ÷ B's score

Required decimal = 75 ÷ 54

Required decimal = 25 ÷ 18 ≈ 1.3889

∴ The correct answer is 1.3889.

Alternate Method

Given:

Maximum marks = 100

B's score = 54

A's score = 75

Formula Used:

Percentage as a ratio = Target Value ÷ Base Value

B A Score = 54 Score = 75 Ratio (A/B) = 75 ÷ 54 = 1.3889

Calculations:

⇒ The problem asks what percentage of B's score is A's score.

⇒ Target value = A = 75

⇒ Base value = B = 54

⇒ Decimal value = 75 ÷ 54

⇒ Simplifying by dividing both numerator and denominator by 3:

⇒ Decimal value = 25 ÷ 18

⇒ Decimal value = 1.3888...

⇒ Rounding off to 4 decimal places, we get 1.3889

∴ The correct answer is 1.3889.

Additional Information

Percentage Base Identification

When a question asks "what percentage of X is Y", the quantity following the word "of" (which is X) is the base. The format is (Y ÷ X) × 100.

Decimal to Percentage Conversion

To convert a decimal to a typical percentage format, you multiply it by 100. In certain exam questions, percentages are presented in their raw decimal ratio form without the percent sign.

Simplifying Fractions

It is always beneficial to simplify fractions to their lowest terms before performing long division to make calculations faster and more error-free.

The pattern followed here is:

Thus, the missing term in the sequence is UQL 30.

Hence, the correct answer is Option 1.

The logic followed here is:

Thus, the missing term in the series is IVK.

Hence, the correct answer is Option 2.

The correct answer is Global Family Day.

Key Points

• Global Family Day is celebrated every year on 1 January to promote the concept of global unity and peace.
• The day emphasizes the importance of family and encourages people around the world to come together as one global family.
• The concept of Global Family Day originated from the book titled "One Day in Peace" by Linda Grover, which inspired the celebration of unity and harmony.
• It was officially recognized in the United Nations Millennium celebrations in the year 2000.
• Global Family Day is observed by sharing meals, spreading messages of peace, and participating in activities that promote love, respect, and understanding among people worldwide.

Additional Information

• Origins of Global Family Day:
• The idea of Global Family Day was inspired by the book "One Day in Peace" written by Linda Grover, which encouraged people to envision a peaceful world.
• It was first observed in the year 2000 during the UN Millennium celebrations as a day dedicated to peace and unity.
• Since then, it has been celebrated annually on 1 January across the globe.
• Significance of Global Family Day:
• The day serves as a reminder of the importance of family values and the interconnectedness of humanity.
• It promotes messages of global unity, peace, and tolerance among different cultures, religions, and nations.
• People engage in activities like sharing meals, participating in community events, and spreading love and positivity.
• Other Observances on 1 January:
• New Year's Day: Celebrated worldwide as the beginning of the new year.
• Various religious and cultural celebrations also take place on this day, marking the start of the year according to specific traditions.
• Comparison with other days:
• World Health Day: Observed on 7 April every year to promote global health awareness.
• Earth Day: Celebrated on 22 April to demonstrate support for environmental protection.
• International Yoga Day: Observed on 21 June to promote the benefits of yoga for physical and mental well-being.

Important Points

• Peace and Unity: Global Family Day promotes the idea of peace and unity in a world often divided by conflicts.
• Participation: People from all walks of life are encouraged to participate in activities that foster love, respect, and understanding.
• Global Impact: The day highlights the importance of addressing global challenges such as poverty, inequality, and violence through shared efforts.
• Symbolic Start: Celebrating Global Family Day on 1 January symbolizes the beginning of a year filled with hope, cooperation, and harmony.