NDA General Ability Test 3 Sep 2023 Official Paper (Previous Year Paper)

The correct answer is “lashed".

Key Points

• The term "lashed" is used to convey a strong or intense impact or effect, befittingly describing what monsoons do, which is to hit areas with intense rainfall.
• Out of the provided options, "flourished", "occupied", and "dried", fail to accurately represent the intensiveness and the nature of a monsoon. The monsoon does not simply "flourish" or "dry" but instead comes with considerable power and impact, hence "lashed" is an apt description.
• Moreover, the term "lashed" fits well with the resulting effect mentioned in the sentence as 'flash floods', thus making the flow of information more coherent and logical.

Hence, the correct answer is 'Option 1’.

The correct answer is “confronts".

Key Points

• The term 'confronts' indicates that today's challenges face us directly and require immediate attention, making it more appropriate for this context as it pertains to facing and addressing difficulties.
• The other options, such as 'supports', 'conflict', or 'convince', infer improper or misguided meanings in this context.
• The term 'conflict' or 'convince' gives an inappropriate portrayal of the relationship between the challenges and 'us', while 'supports' does not make sense because challenges do not typically support us.
• Therefore, the term 'confronts' is the most appropriate choice as it maintains the expression of the predicament and the need for understandable solutions.

Hence, the correct answer is 'Option 3’.

The correct answer is “distance".

Key Points 

• 'Distance' in this context metaphorically represents the whole extent of a challenging or difficult task or journey. • Choices like 'way', 'far' or 'route', do not appropriately express the concern about completing a tough course.
• While 'way' and 'route' indicate a path or course to be followed, they do not inherently convey the concept of completion. The term 'far' is vague and does not denote the idea of a complete journey clearly.
• Therefore, in this context, 'distance' meets the requirement, as it accurately depicts the completion or entire span of a difficult course.

Hence, the correct answer is 'Option 2’.

The correct answer is “extent".

Key Points 

• The word 'extent' represents the degree, size, or range of something - in this case, the degree of advancement made in agricultural productivity, which perfectly fits the intended meaning of the sentence.
• The other choices - 'context', 'distance' and 'syntax' - do not accurately represent what the sentence intends to say. 'Context' might be used to explain the background or circumstances, 'distance' conveys a physical or metaphorical span, and 'syntax' pertains to arrangement of words and phrases. 'Extent', on the other hand, expresses the impressive range or level of advancements made in agricultural productivity.
• Therefore, 'extent' is the most appropriate choice that maintains the coherence and clarity of the sentence.

Hence, the correct answer is 'Option 1’.

The correct answer is “explores".

Key Points 

• 'Explores' is suitable for the context because it typically means investigating, examining, or inspecting, and in this case, it refers to a thorough investigation of the systems for water appropriation and agricultural practices.
• The options 'confuses', 'enhances', and 'controls' are not suitable for this context. 'Confuses' implies misunderstanding or lack of clarity, which is not the intent. 'Enhances' implies improvement, which is not the purpose of an essay. 'Controls' suggests regulation or governance, which is not applicable here.
• In contrast, 'explores' accurately captures the comprehensive exploration and examination of the topic in the essay.
• Hence, the term 'explores' makes the sentence meaningful and deeply insightful, since the aim of an essay is to explore its subject in depth.

Hence, the correct answer is 'Option 4’.

The correct answer is “stabilise".

Key Points 

• The term 'stabilise' is the most appropriate in this context as it implies maintaining or bringing something to a consistent or unchanging state, which here, refers to controlling the population growth.
• 'Sterilise', 'stratify', and 'establish', are not fitting as they are misdirected in the context. 'Sterilise' is a strong term that implies a sterilisation process which isn't the subject here. 'Stratify' refers to arranging something in layers which isn't applicable to population control. 'Establish' means to set up or start something which also is unrelated.
• Therefore, 'stabilise' accurately reflects the success of population control strategies implemented in India through family planning programmes.

Hence, the correct answer is 'Option 2’.

The correct answer is “threshold".

Key Points 

• 'Threshold' demonstrates the concept of crossing a limit or starting a new phase, accurately representing the transition from childhood to adulthood during adolescence.
• Other options like 'position', 'condition' and 'period' do not convey the exact sense of the transition. 'Position' and 'condition' do not showcase a transition and 'period' refers to a span of time.
• Therefore, 'threshold' is the fitting choice as it accurately represents this transition phase in the life of an individual.

Hence, the correct answer is 'Option 1’.

The correct answer is “exploit".

Key Points 

• 'Exploit' implies the act of making full use of and deriving benefit from resources. In this context, it is used to convey the historical fact of British colonial rule over India.
• Other choices like 'spoil', 'implore', and 'drill' do not fit into the context properly. 'Spoil' means to damage, 'implore' refers to begging earnestly or desperately, and 'drill' refers to drilling holes which is not a relatable context.
• Therefore, in the historical context of the British rule in India and their exploitation of India's resources, 'exploit' is the correct choice.

Hence, the correct answer is 'Option 3’.

The correct answer is “extinction".

Key Points 

• 'Extinction' pertains to species and it represents the state of a species being wiped out completely from existence. In the given context, the threat is to the existence of endangered species so, 'extinction' is the most fitting term.
• Other choices, such as 'distinction', 'complication', and 'completion', are not suitable here. 'Distinction' pertains to uniqueness or difference, 'complication' refers to the emergence of an unexpected problem, and 'completion' conveys the end of a process, not species.
• Therefore, 'extinction', which is directly linked to the survival of species, is the appropriate choice for the context.

Hence, the correct answer is 'Option 2’.

The correct answer is “transformed".

Key Points 

• 'Transformed' means to change in form, nature, or appearance. According to the first law of thermodynamics, energy can be transferred or transformed from one form into another.
• 'Reduced', 'induced', and 'performed' are not applicable in this context. 'Reduced' means to make something smaller or less in amount; 'induced' refers to the fact of causing something to occur; and 'performed' means to carry out, accomplish, or fulfil.
• The word 'transformed' is most suitable as it is in context with the given law, which states that energy can change its form while its total amount stays the same.

Hence, the correct answer is 'Option 4’.

The correct answer is "jam common breakfast items".

Key Points

• In part (b), "are" is missing between "jam" and "common". The correct sentence should be "Bread, butter, and jam are common breakfast items."
• The verb "are" is needed to establish the fact that bread, butter, and jam are understood as common breakfast items.
• English grammar demands that there should always be a verb in a sentence. In this case, "are" serves as the verb, making the sentence meaningful.
• In addition, "are" unifies the separate subjects - bread, butter, and jam, and links them to their predicate, making the sentence logical.

Hence, the correct answer is 'Option 2'.

The correct answer is 'No Error'.

Key Points

• In part (a), the use of "is" is correct. Even though "dollars" is in plural form, the total sum of money is considered as a singular entity hence the use of "is" and not "are".
• In part (b), "the prize money being offered" is grammatically correct. It provides information about the prize money and is appropriately linked to part (a).
• In part (c), "by the game show hosts" correctly states the people offering the money and is grammatically correct.
• After analyzing all parts, we can infer that the whole sentence has correct usage of grammar.

Hence, the correct answer is 'Option 4'.

The correct answer is "create up the number of days".

Key Points 

Part (b) should be "make up the number of days".

"Create" is used to bring something into existence, but when you’re talking about components of something, the right verb is 'make up'.

'Create' is incorrect because you cannot 'create' the number of days, but in reality, 365 days 'make up' or 'form' a year.

The appropriate word "make up" should be used to show that 365 days form a year.

Hence, the correct answer is 'Option 2'.

The correct answer is Option (3) i.e. (c) "an animal is called sharing". 

Key Points 

• The process of removing wool from the body of an animal is referred to as "shearing," not "sharing". So, the correct phrasing should be: 'an animal is called shearing.'
• "Sharing" denotes the act of giving a portion of something to others, which is irrelevant in the given context.
• Here, the phrase "is called sharing" should be corrected to "is called shearing" to show the actual process of removing wool from an animal's body.
• Therefore, the incorrect term "sharing" serves as a grammatical error, distorting the meaning of the sentence.

Hence, the correct answer is 'Option 3'.

The correct answer is "from faraway places to prayed". 

Key Points 

• In part (b), the appropriate form of the verb is "to pray". Hence the sentence should be - "from faraway places to pray".
• 'Prayed' is the past tense of the verb 'pray' and does not follow 'to'. It would be correct if changed to 'prayed at', but the infinitive 'to pray' is more suitable here.
• Increase the use of present tense indicates the action is still valid at the time of speaking, which aligns tidily with 'came', a past tense verb in the first clause.
• To make the second clause align with the first, the infinitive 'to pray' is suitable instead of 'to prayed'.

Hence, the correct answer is 'Option 2'.

The correct answer is "after reading foreword of".

Key Points

• "Foreword of" is incorrect; the correct formation should be 'foreword to'.
• The phrase seemingly suggests that the foreword pertains to the book, not a part of it. In English, the preposition 'to' is used after 'foreword' when mentioning the book it is a part of. Thus, 'the foreword to the book' is the correct version.
• The sentence's grammar should also reflect this relationship, so the preposition "of" should be replaced with "to" to indicate the correct context.
• Hence, the phrase "reading forward of" should be changed to "reading foreword to", making the sentence logically and grammatically correct. Hence, the correct answer is 'Option 1'.

The correct answer is "No errror". 

Key Points

• In this sentence, part (a) "The guidance from the mentors", part (b) "and teachers facilitated the", and part (c) "smooth conduct of elections to the Students' council." are all grammatically sound, and they form a semantically logical sentence.
• All parts of the sentence maintain subject-verb agreement, use appropriate prepositions, and maintain a logical flow among all of its constituent components.
• As there is no grammatical discrepancy, it is safe to conclude that the sentence does not contain any errors.
• After analyzing all parts of the sentence, we find that it adheres to the rules of grammar in all aspects.

Hence, the correct answer is 'Option 4'.

The correct answer is "No error".

Key Points

• Part (a) "The Principal of our school", part (b) "felicitated the students in", and part (c) "the prize distribution ceremony." are grammatically sound. They follow the rules of grammar along with maintaining semantic coherence.
• The sentence has correct usage of verb ("felicitated"), preposition ("in"), and noun ("students", "ceremony").
• Both subject-verb and noun-pronoun agreements are adhered to, and there is a logical flow in the sentence arrangement.
• Thus, no grammatical errors are present in this sentence.

Hence, the correct answer is 'Option 4'.

The correct answer is "it will be the best possible decision".

Key Points 

• Part (c) should be "it would be the best possible decision." as it's better to maintain the consistent usage of hypothetical linguistic "were" in part (a).
• Hypothetical situations in English are often described using 'were' and 'would', even if the subject is singular. This is a feature of the 2^nd conditional grammatical structure.
• Since part (a) uses "If you were" to express a hypothetical situation, part (c) should correspondingly use "would" instead of "will".
• By adopting this change, the consistency of the hypothetical narrative is maintained throughout the sentence, which aligns with English grammatical conventions.

Hence, the correct answer is 'Option 3'.

The correct answer is "They had promised to delivered"

Key Points

• The verb following "to" must be in its base form. Therefore, "to delivered" should be "to deliver".
• The infinitive form 'to deliver' is the correct one to use here. The structure usually follows the pattern of "promise to + verb (in base form)" e.g., promised to deliver.
• The verb "deliver" best suits the context and meets English grammar standards in terms of terminology following "promised to".
• Hence, the sentence should be corrected as "They had promised to deliver".

Hence, the correct answer is 'Option 1'.

The correct answer is 'Option 3' i.e. 'faultfinding'.

Key Points

• The word "captious" means intended to entrap or confuse, implying a tendency to find and call attention to faults, which can also describe a person who is overly critical or hard to please. (दोषारोपण करने वाला)
• Example: A captious teacher can demoralize students with constant criticism.
• "Faultfinding" describes a person who regularly finds fault or criticizes something, often in a nitpicking way. (दोष निकालने वाला)
• Example: She has a faultfinding personality, always pointing out the flaws in every situation.

Therefore, the correct answer is 'Option 3' i.e. 'faultfinding'.

Additional Information

• Worried means experiencing unease or concern about something, typically about an imminent event or situation. (चिंतित)
• Passionate means having, showing, or being compelled by strong feelings or emotions. (उत्साही)
• Jovial means cheerful and friendly, often in a hearty manner. (आनंदित)

The correct answer is 'Option 1' i.e. 'verify'.

Key Points

• "Ascertaining" means to find out definitely; to learn with certainty or assurance; or to verify. (पता लगाना)
• Example: Scientists ascertain facts through careful observation and experimentation.
• "Verify" also means to establish the truth, accuracy, or reality of something. (सत्यापित करना)
• Example: The detective was able to verify the witness's statement.

Therefore, the correct answer is 'Option 1' i.e. 'verify'.

Additional Information

• Invert means to turn upside down or inside out; to reverse the position, order or condition of. (उलटना)
• Increase means to become or make greater in size, amount, intensity, or degree. (बढ़ना)
• Omit means to leave out or exclude (someone or something), either intentionally or forgetfully. (छोड़ना)

The correct answer is 'Option 4' i.e. 'canteen'.

Key Points

• A "commissary" is a store that sells food and supplies on a military base or a dining facility on a military installation. (भंडार)
• Example: The soldiers often gathered in the commissary for meals and discussions.
• A "canteen" is a restaurant or cafeteria that is provided by an institution such as a military camp, college, factory, or company for its soldiers, students, staff, etc. (कैंटीन)
• Example: The workers usually have lunch at the company's canteen.

Therefore, the correct answer is 'Option 4' i.e. 'canteen'.

Additional Information

• An office is a room, set of rooms, or building used for non-manual work such as clerical, administrative, or professional work. (कार्यालय)
• Field refers either to an open land area free of woods and buildings or to a branch of study or expertise. (मैदान/ क्षेत्र)
• Playground is an outdoor area for children to play. (खेल का मैदान)

The correct answer is 'Option 2' i.e. 'dissected'.

Key Points

• "Dismembered" involves cutting off the limbs of a body. It generally refers to the act of removing parts from a body. (अंग भंग कर देना)
• Example: In some extreme medical cases, an infected limb may be dismembered to save the patient's life.
• "Dissected" is about cutting something up in order to study its internal parts. In a medical context, it often involves surgical procedures. (विगटन करना)
• Example: Medical students are often required to dissect specimens in anatomy classes.

Therefore, the correct answer is 'Option 2' i.e. 'dissected'.

Additional Information

• Stitched means making, mending, or joining something using stitches with a needle and thread. (सीना)
• Plastered usually refers to applying plaster or a similar substance to a wall, ceiling, or another structure. In some instances, it might also mean 'to bandage' a person. (प्लास्टर से छिपाना)
• Splintered means breaking or cause to break into small sharp fragments. (टुकड़े टुकड़े कर देना)

The correct answer is 'Option 2' i.e. 'accountant'.

Key Points

• A "bursar" is an official in a school or college who is in charge of financial affairs, essentially performing the duties of an accountant. (कोषाध्यक्ष)
• Example: The bursar is responsible for managing the student accounts at the academy.
• An "accountant" is a person whose job is to keep or inspect and record financial accounts. (लेखाकार)
• Example: The accountant is responsible for preparing the annual budget for the company.

Therefore, the correct answer is 'Option 2' i.e. 'accountant'.

Additional Information

• A secretary is a person who assists with correspondence, keeps records, makes appointments, and carries out similar tasks. (सचिव)
• A coach is a person who trains an athlete or a team of athletes. (कोच)
• A trainer is a person who trains people or animals, typically in a specific skill or for a particular purpose. (प्रशिक्षक)

The correct answer is 'Option 3' i.e. 'deceitful'.

Key Points

• "Insidious" means proceeding in a subtle way but with harmful effects. Often used to describe something that is stealthily treacherous or deceitful. (धोखेबाज)
• Example: The insidious enemy infiltrated the group without anyone noticing.
• "Deceitful" refers to being dishonest or having a tendency to lie. (कपटी)
• Example: His deceitful actions made it hard for anyone to trust him.

Therefore, the correct answer is 'Option 3' i.e. 'deceitful'.

Additional Information

• Pious refers to being deeply religious or dutifully observing religious principles. (धार्मिक)
• Inadvertent means not resulting from or achieved through deliberate planning. (अनजाने में)
• Naive means having or showing a lack of experience, understanding, or sophistication. (भोला-भाला/सीधा)

The correct answer is 'Option 3' i.e**. 'inherent'.**

Key Points

• "Intrinsic" refers to belonging naturally; inherent, meaning it is an essential part or characteristic. (स्वाभाविक)
• Example: The intrinsic value of a diamond is determined by its size, color, and clarity.
• "Inherent" means existing in something as a permanent, essential, or characteristic attribute. (अन्तर्निहित )
• Example: The inherent risks of surgery always need to be considered before making a decision.

Therefore, the correct answer is 'Option 3' i.e. 'inherent'.

Additional Information

• Inconsistent means not staying the same throughout. (अस्थिर)
• Peripheral means related to, located in, or constituting an outer boundary or edge. (प्रांतीय)
• Existential means concerned with existence, especially human existence. (अस्तित्ववादी)

The correct answer is 'Option 4' i.e. 'wearying'.

Key Points

• "Onerous" means involving an amount of effort and difficulty that is oppressively burdensome. (बोझिल)
• Example: The onerous responsibilities of the world leaders can often be overwhelming.
• "Wearying" means causing tiredness; tiring. (थकाऊ)
• Example: The wearying journey across the desert took a physical toll on the travelers.

Therefore, the correct answer is 'Option 4' i.e. 'wearying'.

Additional Information

• Smooth means free from difficulties. (सुचारु)
• Complex means consisting of many different and connected parts. (जटिल)
• Risky means full of the possibility of danger, failure, or loss. (जोखिमी)

The correct answer is 'Option 1' i.e. 'Monarch'.

Key Points

• A "potentate" is a monarch or ruler, especially one who has absolute power. (सर्वशक्तिमान शासक)
• Example: The potentate ruled his kingdom with absolute power.
• A "Monarch" is a sovereign head of state, such as a king, queen, or emperor. (महाराज)
• Example: The monarch is the ceremonial head of the state in a constitutional monarchy.

Therefore, the correct answer is 'Option 1' i.e. 'Monarch'.

Additional Information

• Lenient means more merciful or tolerant than expected. (कोमल)
• Liberal means willing to respect or accept behavior or opinions different from one's own. (उदार)
• Democrat is an advocate or supporter of democracy. (लोकतांत्रवादी)

The correct answer is 'Option 2' i.e. 'laziness'.

Key Points

• "Indolence" refers to avoidance of activity or exertion; laziness. (आलस्य)
• Example: His indolence caused him to miss the deadline for the project.
• "Laziness" is the quality of being unwilling to work or use energy; idleness. (आलस)
• Example: Laziness is often the cause of many health issues.

Therefore, the correct answer is 'Option 2' i.e. 'laziness'.

Additional Information

• Difficulty is the state or condition of being difficult i.e. challenging or hard to achieve, manage, or handle. (कठिनाई)
• Ugliness means the quality of being unpleasant or repulsive in appearance. (बदसूरती)
• Helplessness is lack of ability to act effectively; impotence. (असहायता)

The correct answer is 'Option 3' i.e.

Key Points

• A "Principal" refers to the person in charge of a school or other educational institution. (प्रधान)
• Example: The principal is responsible for the overall functioning of the school.
• A "Principle" is a fundamental truth or proposition that serves as the foundation for a system of belief or behavior. (सिद्धांत)
• Example: Honesty is a basic principle that one should always follow.

Therefore, the correct answer is 'Option 3' i.e. 'Principal' means head of an educational institution, and 'principle' means moral rule.

Additional Information

• A belief system refers to a set of mutually supportive beliefs. (धारणा प्रणाली)
• The original sum on which interest is charged is known as the principal amount in financial terms. (मूल राशि)

The correct answer is: 'Plane' means a flat surface, and 'plain' means not elaborate.

Key Points

• 'Plane' refers to a flat or level surface where every point is at the same height. (सपाट सतह)
• Example: The carpenter used a planer to make the wood surface smooth and plane.
• 'Plain' means simple, clear, and not complicated or elaborately decorated. It can also refer to a large area of flat land. (सादा)
• Example: She preferred wearing plain clothes without any fancy embellishments.

Therefore, the correct answer is- 'Plane' means a flat surface, and 'plain' means not elaborate.

Additional Information

• Option 1: Incorrect because 'Plane' does mean a flat surface, but 'plain' does not mean something that flies. 'Plain' correctly defined means not elaborate or adorned.
• Option 3: Incorrect because 'Plane' does not mean something that doesn't fly; it refers to a flat surface. Additionally, 'plain' does not directly mean flat surface but conveys simplicity.
• Option 4: Incorrect because the definitions are swapped. 'Plane' refers to a flat surface, not something not elaborate, and 'plain' signifies simplicity, not a flat surface.

The correct answer is 'Option 3' i.e. 'Pale' means faded or light in shade, and 'pail' means a bucket.

Key Points

• "Pale" often refers to a light shade or hue or to someone looking less colorful than usual due to sickness, shock, fear, etc. (पीला/फीका)
• Example: After hearing the shocking news, he turned pale.
• A "Pail" refers to a bucket-like container with a handle which is used to hold or carry things, particularly liquids. (बाल्टी)
• Example: He carried a pail full of water from the well.

Therefore, the correct answer is 'Option 3' i.e. 'Pale' means faded or light in shade, and 'pail' means a bucket.

Additional Information

• "Inferior" means lower in rank, status, or quality. (हीन)
• "Unimpressive" means not evoking admiration, interest, or respect. (प्रभावहीन)

The correct answer is 'Option 4'.

Key Points

• "Metal" is a solid material that is typically hard, shiny, malleable, fusible, and ductile, with good electrical and thermal conductivity. (धातु)
• Example: Gold and silver are precious metals.
• "Mettle" is a person's ability to cope well with difficulties; their resilience. (साहस)
• Example: His mettle was tested in the battlefield.

Therefore, the correct answer is 'Option 4' i.e. 'Metal' is a hard shiny material that is a good conductor, and 'mettle' means mental resilience.

Additional Information

• "Malleable" means able to be hammered or pressed permanently out of shape without breaking or cracking. (आघातवर्ध्यमाण)
• "Metallic" means relating to or resembling metal or metals. (धातुमय)

The correct answer is 'Option 2'.

Key Points

• "Hail" is a type of solid precipitation consisting of balls or irregular lumps of ice. (ओला)
• Example: The storm brought with it heavy hail that damaged the crops.
• "Hale" describes someone, especially an old person, who is strong and healthy. (स्वस्थ)
• Example: Despite his age, he is hale and hearty.

Therefore, the correct answer is 'Option 2' i.e. 'Hail' means pellets of frozen rain, and 'hale' means strong and healthy.

Additional Information

• A wind storm refers to a storm with high winds but little or no precipitation. (वायुझड़)
• To greet with enthusiastic approval is to acclamation. (प्रशंसा)

The correct answer is 'Option 4'.

Key Points

• "Conscious" refers to being aware of and responding to one's surroundings. (जागरूक)
• Example: He was conscious of the faint smell of coffee.
• "Conscience" is an inner feeling or voice acting as a guide to the rightness or wrongness of one's behavior. (अंतःकरण)
• Example: His conscience pricked him when he lied to his parents.

Therefore, the correct answer is 'Option 4' i.e. 'Conscious' means aware, and 'conscience' means sense of right and wrong.

Additional Information

• A belief system refers to a set of mutually supportive beliefs. The beliefs may be religious, ideological or philosophical. (विश्वास प्रणाली)
• Presence of mind refers to calmness and quickness under pressure, allowing one to act effectively in an emergency. (सतर्कता)
• Unprincipled action refers to actions not conforming to moral or ethical standards. (अनैतिक क्रिया)

The Correct Answer is Option 1

Key Points

• 'Dissent' refers to having ideas different from general beliefs or official position.(मतभेद)
• Example: The authoritarian regime did not tolerate dissents.
• 'Descent' denotes a movement towards a lower place.(नीचे की ओर जाना)
• Example: The descent of the mountain was more dangerous than the climb.

Therefore, the correct answer is Option 1.

Additional Information

• Option 2, 3, and 4 are incorrect as they mix up the definitions of 'Dissent' and 'Descent'.
• Specifically in Option 4, 'Descent' is not related to having ideas different from general beliefs and 'Dissent' doesn't mean being of acceptable standard.

The Correct Answer is Option 3

Key Points

• 'Devise' means to plan or invent something by careful thought. (योजना बनाना)
• Example: She devised a plan to conquer the market.
• 'Device' refers to a piece of equipment meant for accomplishing a specific task.(उपकरण)
• Example: He turned off his device before the meeting started.

Therefore, the correct answer is Option 3.''Device' means a piece of equip-ment meant for accomplishing a specific task, and 'devise' means finding a new way to do something'.

Additional Information

• Option 1, 2, and 4 incorrectly intermix the meanings of 'Devise' and 'Device'.
• For instance, in Option 4, 'Device' does not mean finding a new way to do something and 'Devise' is not a piece of equipment.

The Correct Answer is Option 2

Key Points

• 'Discrete' means separate and distinct.(पृथक)
• Example: These tasks can be broken down into discrete segments.
• 'Discreet' stands for careful and circumspect in one's speech or actions.(सूचक)
• Example: They were discreet in their dealings.

Therefore, the correct answer is Option 2 i.e. ''Discrete' means separate and distinct categories of objects, and 'discreet' means maintaining confidentiality'.

Additional Information

• Option 1, 3, 4 inaccurately swap the meanings of 'Discrete' and 'Discreet'.
• For example, in Option 3, 'Discrete' does not mean being careful and 'Discreet' does not mean separate and distinct categories of objects.

The Correct Answer is Option 1

Key Points

• 'Eminent' refers to a person who is famous and respected within a particular sphere.(प्रमुख)
• Example: She is an eminent scholar in the field of physics.
• 'Imminent' means about to happen.(सन्निकट)
• Example: They were in imminent danger of being swept away.

Therefore, the correct answer is Option 1.''Eminent' means important and famous, and 'imminent' means something about to happen'.

Additional Information

• Option 2, 3, 4, incorrectly interchange meanings of 'Eminent' and 'Imminent'.
• For instance, in Option 2, 'Eminent' does not mean something unpleasant about to happen and 'Imminent' does not refer to an important and famous person.

The correct answer is 'hard'.

Key Points

• Malleable refers to a material's property of being transformed into various forms or shapes without breaking. This property is often attributed to materials, especially metals such as gold and silver. (लचीला)
• Example: Gold is highly malleable, allowing it to be crafted into intricate jewellery designs.
• On the contrary, 'hard' refers to the quality of an object being solid, firm, and rigid, not easily penetrated or moulded. This definition makes 'hard' the closest antonym of the term 'malleable' among the available options. (सख्त)
• Example: The diamond is so hard that it can be used to cut through other materials.
• Hence, the closest antonym is 'hard'.

Therefore, the correct answer is “Option 1".

Additional Information

• Strong (मजबूत): It refers to the ability to withstand force or pressure. However, it does not directly contrast with 'malleable' since a material can be both strong and malleable.
• Tender (नरम): Generally used to describe softness or sensitivity, but doesn't serve as an opposite term to malleability.
• Weak (कमजोर): It refers to something lacking strength, but it doesn't serve as the opposite term to malleability. A material could be malleable and still be weak in terms of its resistance to force or pressure.

The correct answer is 'regard'.

Key Points

• Neglect refers to paying no attention to or ignoring something. When you neglect something, you fail to care for it or give it the attention it requires. (उपेक्षा)
• Example: If you neglect your health, it can lead to serious health issues in the future.
• The opposite of neglect is to pay attention, or be mindful of something, which fits the definition of the word 'regard'. (ध्यान देना)
• Example: If you regard the teacher's instructions, you'll do well on the test.
• Hence, the correct antonym is 'regard'.

Therefore, the correct answer is “Option 3".

Additional Information

• Disregard (अवहेलना): This word is actually similar to 'neglect', not opposite. It means to pay no attention to something or to ignore it.
• Ignore (नजरअंदाज करना): This is another synonym for neglect, not an antonym. It denotes a deliberate act of not paying attention or disregarding.
• Overlook (अनदेखा करना): This means to miss or fail to notice something, similar to 'neglect'. So it is not the opposite of neglect.

The correct answer is 'modest'.

Key Points

• Ostentatious refers to something or someone that is highly showy, intrusive or pretentious in order to attract attention or impress. It usually holds a negative connotation and implies an excessive display of wealth, luxury, or vanity. (दिखावटी)
• Example: He drove an ostentatious car, bright red, and decorated with flashy rims.
• The opposite of ostentatious is something or someone who is unassuming, low-key or avoids drawing attention, which fits the definition of the word 'modest'. (संयमी)
• Example: Despite his success, he remained a modest individual who preferred a simple lifestyle.
• Hence, the correct antonym is 'modest'.

Therefore, the correct answer is “Option 2".

Additional Information

• Tawdry (सस्ता और बेकार): This word generally refers to something cheap and of poor quality, often with a gaudy or flashy appearance. It doesn't necessarily reflect the opposite of ostentatious.
• Gaudy (भड़कीला): This is a synonym for ostentatious, not an antonym. It refers to something excessively showy in a tasteless or vulgar way.
• Apparent (स्पष्ट): This means clearly visible or understood, having an appearance of truth or fact. It doesn't have a direct contrast with 'ostentatious'.

The correct answer is 'mild'.

Key Points

• Excruciating refers to something or someone causing great pain or anguish, it is used to indicate something extremely distressing or difficult to bear. (अत्यंत कष्टदायक)
• Example: The hike up the mountain was excruciating to the inexperienced climbers due to its steepness and their lack of preparation.
• The opposite of excruciating is something gentle, not severe or extreme, which fits the definition of the word 'mild'. (हल्का)
• Example: The medicine had only a mild effect, just enough to alleviate the pain but not enough to make it disappear completely.
• Hence, the correct antonym is 'mild'.

Therefore, the correct answer is “Option 4".

Additional Information

• Gnawing (चबाने): It generally refers to a continuous or troubling discomfort or worry. It is more related to 'excruciating' than being an opposite.
• Gruelling (कठिन): It refers to something that is extremely tiring and demanding. It is not the opposite, but rather a synonym to 'excruciating'.
• Harrowing (हताशाजनक): This word means distressing or grievous. It is synonymous with 'excruciating', not antonymous.

The correct answer is 'wearying'.

Key Points

• Refreshing refers to something that is invigorating, rejuvenating, or provides a sense of renewed energy. (ताजगी भरा)
• Example: A refreshing walk in the morning can set a positive tone for the day.
• The opposite of refreshing is something that causes fatigue or exhaustion, which fits the definition of the word 'wearying'. (थकाऊ)
• Example: Long hours of studying can be wearying for students and may lead to decreased productivity.
• Hence, the correct antonym is 'wearying'.

Therefore, the correct answer is “Option 2".

Additional Information

• Conniving (षड्यंत्रकारी): This term is not related to the term 'refreshing'. It refers to secretly cooperating or plotting, typically for malicious purposes.
• Revivifying (पुनर्जीवित करना): This serves as a synonym for 'refreshing', not an antonym. It means to give new life or vigor to.
• Rejuvenating (नवजीवन देनेवाला): This is another synonym for 'refreshing'. It means to make someone or something look or feel better, younger, or more vital.

The correct answer is '1, 2 and 3'.

Key Points

• The passages depict that people tend to exploit resources imprudently under three primary conditions: when there's plenty of the resource, when there's a possibility of substitution, and when they feel that others might overuse the resource.
• First, when the resource catchment is extensive, people don't notice the impact of degrading a particular portion, consequently affecting resource utilization less thoughtfully.
• Second, the author implies that if people see the possibility of simply substituting one resource with another when it gets depleted, they do not feel the need to use the original resource wisely.
• Third, the perceived lack of control over the resource, fearing that others may deplete it, leads individuals to potentially act in their immediate self-interest rather than use the resource prudently.

Therefore, the correct answer is ‘Option 4’.

Additional Information

• Option 1 alone is partially correct, but it doesn't cover all conditions presented in the passage. The author emphasized that people's unwillingness to use resources prudently is based not only on the fear of other people overusing the resource, but also on the scale of the resource availability and the perception of its substitutability.
• Similarly, option 2 alone or option 3 alone might explain some parts of the situation, but they fail to address all the conditions that contribute to people's lack of motivation to use resources prudently.
• Option '2 and 3 only' might seem correct, however, given that the author clearly defined three distinct conditions, omitting the first one would fail to capture the full view presented in the passage. Hence, it is not a suitable answer either.

The correct answer is 'When the resources use has little impact'.

Key Points

• According to the passage, people exhaust resources when they perceive that their actions (i.e., utilisation of resources) would not significantly harm their surrounding because the resource availability is vast.
• The passage suggests that exhaustive use of a resource is more likely if degradation of a particular portion affects the individuals very little because the resource is in abundance.
• It's also mentioned that the exhaustive use of resources is typical when a "resource catchment" is extensive, basically, where the resources are abundant. So, when individuals believe their usage has an insignificant impact due to its extent, they tend to utilize the resources exhaustively.

Therefore, the correct answer is ‘Option 3’.

Additional Information

• Option 1: The passage doesn't mention anything about NGOs facilitating the substitution of resources. Therefore, this option is not relevant in this context.
• Option 2: There is no mention in the passage about people exhaustively using resources when they are about to expand. This option is also irrelevant.
• Option 4: The passage suggests that people are unlikely to use resources prudently until they perceive their execution as having a significant impact (among other conditions). The aspiration for sustainable development was not mentioned as a factor influencing the exhaustive use of resources.

The correct answer is 'indifferently'.

Key Points

• The passage suggests that people typically pursue self-interest and this influences their usage of renewable resources in such a way that it is not prudent or sustainable.
• It implies that the focus on self-interest leads people to use resources indifferently, without sufficient attention to the long-term impact and sustainability of the resources.
• The term "indifferently" means without interest or concern and is suitable to characterize the impact of self-interest on renewable resource use according to this passage.

Therefore, the correct answer is 'Option 4'.

Additional Information

• Option 1 (positively): This option does not apply since the passage clearly indicates that the self-interest of people impacts the use of renewable resources in a non-prudent and unsustainable manner.
• Option 2 (erratically): The passage does not suggest that the self-interest of people leads them to use resources 'erratically' or unpredictably. Instead, there are specific conditions described that determine their behavior.
• Option 3 (affirmatively): The passage doesn't indicate that people affirmatively respond to self-interest in terms of renewable resource usage. Their response, as depicted, is indifferent and unsustainable.

The correct answer is 'believe in conservation and re-production of resources'.

Key Points

• The passage indicates that people who are rooted in a locality and have control over their local resource base are most likely to meet all the prerequisites for sustainable resource use.
• It suggests such individuals are committed to behaviors that promote conservation of biodiversity within their local regions, implying a belief in the conservation and prudent use of resources.
• Therefore, the author identifies individuals rooted in a locality as those who value their resources and commit towards sustainable practices.

Therefore, the correct answer is 'Option 3'.

Additional Information

• Option 1: The passage doesn't imply that people living in a locality cause harm to the available resources. On the contrary, they are described as the ones who are most likely to use resources sustainably.
• Option 2: While local individuals may generate some resources, that's not the focus of the passage. The passage primarily emphasizes their commitment to resource sustainability and conservation, not necessarily creation or generation of resources.
• Option 4: The passage contradicts this option, as it specifically states that people rooted in a locality are the ones most likely to use resources in a prudent, not free, fashion.

The correct answer is 'exhaust'.

Key Points

• 'Deplete' is a verb that means to use up the supply or resources of something. ("उपयोग कर देना" or "खत्म कर देना").
• Example: Overfishing has severely depleted the stocks of fish in the ocean.
• 'Exhaust' aligns closely with the meaning of 'deplete'. It means to use up (resources or reserves) completely. ("समाप्त करना" or "खत्म करना").
• Example: The long journey had exhausted our food supplies.
• Hence, the correct synonym for 'deplete' is 'exhaust'.

Therefore, the correct answer is "Option 1".

Additional Information

• 'Complete' means to finish making or doing. (समाप्त करना" or "पूरा करना"). While it has a similar connotation as 'deplete' and 'exhaust' in terms of finishing something, it doesn't carry the implication of using up resources.
• 'Replete' means full; filled up ("परिपूर्ण" or "भरपूर"). This term has an entirely opposite meaning to 'deplete' as it implies being filled up or ample, not using up.
• 'Desperate' has no connotation related to using up resources. It means having a great need or desire for something. ("व्याकुल" or "तरसता हुआ"). It indicates urgency and desire rather than a state of depletion or exhaustion.

The correct answer is dust particles in the air scatter light into our eyes.

Key Points

• When sunlight enters a dusty room through the window, its path becomes visible to us.
• Small dust particles present in the air of the room scatter rays of light around the room.
• This is called the Tyndall effect.
• The flow of light rays through the trees that you see is due to the scattering of light.
• Particles in the atmosphere, such as dust, water droplets, and air molecules, scatter sunlight in different directions.
• This scattering effect is more pronounced for shorter wavelengths of light, such as blue and violet, which is why the sky appears blue during the day.

Additional Information

• Light can travel in both medium and vacuum. But there will be no such particle in a vacuum that light cannot collide with and be reflected.
• Light in the air can be reflected after hitting dust or some other particle, so light in the air is visible.
• Light can be considered as waves.
• Light waves travel in different wavelengths and depending on the wavelength, different light has different colors.
• Polarization of light is a property exhibited by transverse waves.
• Light waves that travel in only one plane are called polarized light waves.
• The process of converting unpolarized light waves into polarized light waves is called polarization of light.

The correct answer is Light travels much faster than sound.

Key Points

• Light travels at a much higher speed than sound.
• The speed of light in a vacuum is 3,00,000 km/s, while the speed of sound varies depending on the medium but is much slower (e.g., around 343 meters per second in air).
• When lightning occurs, the light from the flash reaches the observer almost instantaneously, while the sound of thunder takes some time to travel through the air.
• The time gap between seeing the lightning and hearing the thunder can be used to estimate the distance of the lightning strike.

Additional Information

• According to Einstein's special relativity, the speed of light has a unique state: it is a fundamental characteristic of our universe, representing the maximum speed at which information can travel from one place to another.
• The twinkling of a star is due to the atmospheric refraction of starlight.
• The starlight, on entering the earth’s atmosphere, undergoes refraction continuously before it reaches the earth.
• The atmospheric refraction occurs in a medium of gradually changing refractive index.
• Since the atmosphere bends starlight towards the normal, the apparent position of the star is slightly different from its actual position.

Concept:

Ohm's Law:

• Ohm's Law states that the current through a conductor between two points is directly proportional to the voltage across the two points.
• Formula: V = I × R
• Resistance (R): A measure of the opposition to current flow in an electrical circuit. SI Unit: Ohm (Ω).
• Current (I): The flow of electric charge. SI Unit: Ampere (A). Formula: I = V / R
• Voltage (V): The potential difference across the terminals of the heater. SI Unit: Volt (V).

Calculation:

Given,

Voltage across the heater, V₁ = 220 V

Current through the heater, I₁ = 0.5 A

Voltage across the heater after reduction, V₂ = 120 V

First, find the resistance of the heater using Ohm's Law:

R = V₁ / I₁

⇒ R = 220 V / 0.5 A

⇒ R = 440 Ω

Now, find the current through the heater when the voltage is reduced:

I₂ = V₂ / R

⇒ I₂ = 120 V / 440 Ω

⇒ I₂ = 0.2727 A

∴ The current through the heater is approximately 0.27 A when the potential difference is reduced to 120 V.

The correct answer is Nichrome.

Key Points

• Nichrome is a nickel-chromium alloy and is a common material for heating elements in electrical appliances, including electric irons.
• It has high electrical resistance and can withstand high temperatures without oxidizing or breaking down.
• Nichrome, as it is a commonly used material for the heating element in electric irons due to its desirable electrical and thermal properties.
• The heating element in an electric iron is an alloy consisting of 80% nickel and 20% chromium.
• The melting point of nichrome is 1400ºC with high resistance which makes this element best for use as a heating element.
• Nichrome is characterized by a silver-gray color and is resistant to corrosion and wear, being very durable.
• Its resistance to oxidation makes nichrome a popular material for use in heating elements.
• Nichrome wire is an ohmic conductor.

Additional Information

• Constantan is a copper-nickel alloy.
• It is commonly used in resistance wires for temperature measurement devices such as thermocouples.
• However, it is not commonly used as a heating element in electric irons.
• Tungsten has a very high melting point and is commonly used in incandescent light bulbs.
• However, it is not commonly used as a heating element in electric irons.
• Copper has a relatively low melting point and is an excellent conductor of electricity, but it is not commonly used as a heating element in electric irons because it does not provide the necessary resistance for effective heating.

The correct answer is 0.75 m.

Key Points

• To see one's full image in a vertical plane mirror, a person's eye level must be at the halfway point between the top and bottom of the mirror.
• This means that the minimum height of the mirror should be half of the height of the person.
• This way, the complete image of the person will be visible in the mirror.
• Height of Sita is 1.5 meters
• The mirror's height should be 1.5/2 = 0.75 m

The correct answer is Zinc.

Key Points

• Galvanization is a method of protecting steel and iron from rusting by applying a thin layer of zinc to them.
• Galvanization also provides improved corrosion resistance to environmentally exposed parts.
• This is a very common way to prevent iron from rusting.
• This can be done by dipping the protected metal in hot, molten zinc or by the process of electroplating.
• Protecting iron and steel from rust by coating with molten zinc.
• Zinc coating protects the surface of the part from the environment, preventing corrosion and weathering.
• The material is loaded onto jigs before being dipped into molten zinc at about 450 degrees until the working temperature is the same as that of zinc.
• During this process, molten zinc reacts with the surface of the steel to form a series of zinc/iron alloys.
• Galvanization helps extend the life of steel parts by creating a membrane between the metal and air, preventing the accumulation of iron oxide on the steel layer.

Additional Information

• Sedimentation-
• The settling of particles present in a fluid (liquid or gas) on the ground is called sedimentation.
• Sedimentation occurs due to gravitational force or centrifugal force on particles suspended in liquid.
• Neutralization-
• The reaction of acid with base is called a neutralization reaction.
• The products of this reaction are salt and water.
• For example, the reaction of hydrochloric acid (HCl) with sodium hydroxide (NaOH) produces a solution of sodium chloride (NaCl) (salt) and a few additional water molecules.
• Corrosion:
• Corrosion is the oxidation-induced deterioration of certain materials, both metals and non-metals.
• When a material comes in contact with air or certain chemicals, it can corrode.
• Erosion is a type of corrosion that can occur in materials such as polymers and ceramics.
• Rusting:
• The oxidation of iron in the presence of air and moisture is called rusting.
• This is an example of corrosion.
• Rust is an iron oxide, a reddish-brown oxide that forms when iron and oxygen react in the presence of water or air moisture.

The correct answer is Steel.

Key Points

• Steel is an alloy that contains carbon as one of its components.

Additional Information

• Brass is an alloy made of copper and zinc, which are both metals.
• There is no non-metal present in brass.
• Bronze is an alloy of copper and tin, which are both metals.
• Like brass, bronze contains no nonmetals.
• Amalgam includes 40–60% silver, 27–30% tin 13–30% copper and 1% zinc set with mercury.
• Steel is an alloy of iron and carbon, sometimes with other elements added.
• Carbon is a non-metal, so steel does has a non-metal as one of its components. Hence, the correct answer will be option 4.

Some common mixtures are :

The correct answer is Carbon.

Key Points

• Buckminsterfullerene:
• Fullerene is a carbon allotrope consisting of fused rings of five to seven atoms and a molecule composed of carbon atoms linked by single and double bonds to form a closed or partially closed lattice.
• Buckminsterfullerene has the formula C60 and is a type of fullerene.
• It is composed of twenty hexagons and twelve pentagons and has a cage-like fused-ring structure (truncated icosahedron) that resembles a soccer ball.
• Structure:
• The C60 structure is made up of 60 carbon atoms that are linked together to form a hollow cage.
• The construction has 32 facets, 20 of which are hexagons and 12 of which are pentagons.
• No two pentagons have the same vertex.

Additional Information

• The property of an element which exists in more than one physical form is called allotrope and the forms are called allotrope.
• Carbon shows allotropy due to chaining, which is the joining of atoms of the same element to each other to form long chains.
• Various allotropes of carbon exist in nature, including diamond, graphene, fullerene, C60, C70, amorphous carbon, Cu carbon, Lonsdaleite, and carbon nanotubes.
• Diamond
• ​The structure of diamond is tetrahedral.
• Each carbon atom is linked to four other carbon atoms by covalent bonds to form a giant crystal lattice.
• Due to its tetrahedral structure, diamond is one of the hardest known materials.
• It has a high refractive index, reflects light internally and hence shines.
• Graphene:
• ​It is a single-layer compound derived from graphite.
• In its hexagonal lattice, each carbon is bonded to three others, giving up an extra electron.
• Graphene is an excellent conductor of electricity and heat due to its extra electrons.

The correct answer is option 3.

Key Points

• A wafer is a thin slice of semiconductor material crucial for creating integrated circuits in electronic devices.
• Therefore, being a semiconductor material, the accurate depiction of the relationship between current (I) and voltage (V) will be:

As the graph for reverse bias is absent in the options, selecting the graph for forward bias, namely option 3, is the appropriate choice.

Additional Information

• Wafers serve as the foundational substrate for embedding integrated circuits, making them the core of electronic devices.
• Raw silicon undergoes a series of steps to transform into a single crystal substrate.
• These steps aim to eliminate impurities like iron, aluminum, and boron.
• Single crystal samples with a specific orientation are produced through crystal growing.
• The single crystal samples are sliced into thin portions known as wafers.
• Various substances are diffused and deposited into the wafers to construct microcircuits.

The correct answer is 1%.

Key Points

• Green plants capture about 1% of the energy of sunlight falling on their leaves for the process of photosynthesis.
• This energy is converted into chemical energy in the form of food. At subsequent levels only 10% of the energy is available.

Additional Information

• Photosynthesis is the process by which green plants produce carbohydrates and release chemical energy by absorbing carbon dioxide, water, and sunlight in the presence of chloroplasts.
• Sunlight is the main source of energy for photosynthesis.
• The gas that plants absorb during photosynthesis is Carbon dioxide.
• The gas that plants release during photosynthesis is Oxygen.
• The gas that plants absorb during respiration is Oxygen.
• The gas that plants release during respiration is Carbon dioxide.
• The rate of photosynthesis is maximum - Red light.
• Rate of photosynthesis is minimum – Green light.
• The pigment in chloroplasts that gives plants their green color is Chlorophyll.
• The only metal present in chlorophyll is Magnesium.

The correct answer is It is a highly endothermic reaction.

Key Points

• In the given reaction, aluminum (Al) displaces iron (Fe) from iron(III) oxide (Fe2O3), resulting in the formation of iron and aluminum oxide. Hence, it is an example of displacement reaction.
• Displacement reactions, such as the one shown in the equation, are typically exothermic.
• The transfer of electrons between the reactants releases energy. It means it is an exothermic reaction. Hence, option 2 is incorrect.
• In this case, aluminum is oxidized (loses electrons), and iron(III) oxide is reduced (gains electrons).
• The overall reaction is exothermic.
• In the given reaction, iron(III) oxide (Fe2O3) is reduced to form iron (Fe), indicating that Fe2O3 acts as an oxidizing agent, as it accepts electrons from aluminum.
• The reaction between iron(III) oxide and aluminum is used in thermite welding, which is a method of joining metal pieces, including railway tracks.
• The intense heat generated during the reaction melts the iron and aluminum oxide, facilitating the welding process.

The correct answer is A - 3, B - 2,C - 4, D - 1.

Key Points

• Electrolysis of water - Decomposition reaction
• Burning of coal - Combination reaction
• Iron nail immersed in copper sulfate solution - Displacement reaction
• Addition of barium chloride solution to aluminum sulfate solution - Double displacement reaction

Additional Information

• Decomposition Reaction:
• A decomposition reaction involves the breakdown of a single compound into simpler substances.
• This process often requires external energy, such as heat, light, or electricity.
• For example, in the electrolysis of water, the compound water (H₂O) decomposes into hydrogen gas (2H₂) and oxygen gas (2O₂) when an electric current is passed through it.
• Combination Reaction:
• ​A combination reaction is characterized by the union of two or more substances to form a new compound.
• This type of reaction typically releases energy.
• In the burning of coal, carbon in coal (C_coal) combines with oxygen (2O₂) in the air to produce carbon dioxide (CO₂).
• Displacement Reaction:
• A displacement reaction involves the replacement of one element in a compound by another element.
• This type of reaction often occurs when a more reactive element displaces a less reactive element from its compound.
• For instance, when an iron nail (Fe) is immersed in copper sulfate (CuSO₄), iron displaces copper, resulting in the formation of iron sulfate (FeSO₄) and copper.
• Double Displacement Reaction:
• ​A double displacement reaction entails the exchange of ions between two compounds, leading to the formation of two new compounds.
• This type of reaction is common in aqueous solutions.
• In the addition of barium chloride (BaCl₂) to aluminum sulfate (Al₂(SO₄) ₃), barium sulfate (BaSO₄) and aluminum chloride (AlCl₃) are formed through the exchange of ions between the reactants.

The correct answer is Burning of magnesium ribbon in air.

Key Points

• Burning of magnesium ribbon in air:
• This process involves a chemical reaction.
• When magnesium ribbon burns in the presence of oxygen (from the air), it undergoes a chemical reaction to form magnesium oxide.
• The reaction can be represented as:
• 2Mg + O₂ → 2MgO
• During this process, the chemical composition of the magnesium changes, indicating a chemical reaction.

Additional Information

• Evaporation of petrol:
• Evaporation is a physical process, not a chemical reaction.
• It involves the conversion of a liquid into a vapor without any change in the chemical composition of the substance.
• In the case of petrol, it is the evaporation of the liquid hydrocarbons.
• Dissolution of salt in water:
• ​Dissolving salt in water is also a physical process.
• It is a dissolution or solvation process where the salt crystals break down into ions in the water, but there is no chemical reaction involved.
• Storing of oxygen gas under pressure in a gas cylinder:
• ​Storing oxygen gas under pressure is a physical process related to the compression and storage of gases.
• It does not involve any chemical reaction; it's merely a change in the physical state of the gas.

The correct answer is Iron.

Key Points

• Iron is not highly reactive with cold water.
• It does not react with cold water to liberate hydrogen gas.
• Iron reacts slowly with steam or hot water to form iron(II) oxide and hydrogen gas.
• 3Fe + 4H2O → Fe3O4 + 4H2↑

Additional Information

• Potassium is a highly reactive metal and reacts vigorously with cold water to release hydrogen gas and form potassium hydroxide.
• 2K + 2H2​O → 2KOH + H2​↑
• Calcium is a reactive metal and reacts with cold water to produce calcium hydroxide and hydrogen gas.
• Ca + 2H2​O → Ca(OH)2​ + H2​↑
• Sodium is a highly reactive metal and reacts vigorously with cold water to liberate hydrogen gas and form sodium hydroxide:
• 2Na + 2H2​O → 2NaOH + H2​↑

The correct answer is Solid, liquid, gas.

Key Points

• In the given reaction:
• 2HgO $\stackrel{\Delta}{\longrightarrow}$ 2Hg + O2
• HgO is mercury(II) oxide (red mercuric oxide) and is a solid (s) before the reaction.
• Hg is mercury and is in a liquid (l) state after the reaction.
• O₂ ​ is oxygen gas and is in a gaseous (g) state after the reaction.
• Therefore, the respective states are:
• 2HgO (s) $\stackrel{\Delta}{\longrightarrow}$ Hg (l) + O₂ (g)

The correct answer is Meiosis and fertilization.

Key Points

• Meiosis and fertilization:
• Meiosis is a type of cell division that occurs in the formation of gametes (sperm and egg cells).
• During meiosis, the chromosome number is reduced by half, leading to genetic diversity among the resulting gametes.
• Fertilization then involves the fusion of these gametes, combining genetic material from two different individuals.
• The combination of meiosis and fertilization results in offspring with unique combinations of genes, contributing significantly to genetic diversity.
• Meiosis and fertilization are the two important features of sexual reproduction in higher organisms that create genetic diversity in offspring.

Additional Information

• Mitosis and fertilization:
• Mitosis is a process of cell division that results in two daughter cells with the same genetic information as the parent cell.
• While mitosis plays a crucial role in the growth and repair of tissues, it does not contribute to genetic diversity.
• Fertilization, on the other hand, involves the fusion of gametes (sperm and egg cells) and brings together genetic material from two parents.
• However, since mitosis does not involve the creation of genetically diverse offspring.
• Mitosis and binary fission:
• Mitosis, as mentioned earlier, is a process of cell division that results in genetically identical daughter cells.
• Binary fission is a method of asexual reproduction observed in prokaryotic organisms, where a single cell divides into two identical daughter cells.
• Both mitosis and binary fission do not directly contribute to genetic diversity in offspring.
• Meiosis and conjugation:
• ​Conjugation is a process of genetic exchange in some single-celled organisms, such as bacteria.
• While it involves the transfer of genetic material, it is not a feature of sexual reproduction in higher organisms.
• Meiosis, on the other hand, is a key process in the formation of gametes, contributing to genetic diversity when followed by fertilization.

The correct answer is Mitochondria.

Key Points

• Mitochondria are membrane-bound organelles found exclusively in eukaryotic cells.
• They play a crucial role in cellular respiration, producing energy (ATP) for the cell.
• Prokaryotic cells lack membrane-bound organelles like mitochondria.
• Therefore, the correct answer is mitochondria, as it is a eukaryotic-specific organelle not found in prokaryotic cells.

Additional Information

• Cell wall:
• ​Both eukaryotic and prokaryotic cells can have a cell wall.
• In prokaryotes, such as bacteria, the cell wall is composed of peptidoglycan.
• In eukaryotes, plant cells have a cell wall made of cellulose, and fungi have a cell wall made of chitin.
• Plasma membrane:
• Both eukaryotic and prokaryotic cells have a plasma membrane, which is a lipid bilayer that surrounds the cell and controls the passage of substances in and out of the cell.
• It is a fundamental structure in all types of cells.
• Nucleic acid:
• Nucleic acids, specifically DNA, are found in both eukaryotic and prokaryotic cells.
• However, the organization and location of the genetic material differ between the two cell types.
• Eukaryotic cells have a membrane-bound nucleus that houses their DNA, while prokaryotic cells have a nucleoid region where the DNA is located, but it is not enclosed within a membrane.

The correct answer is Sugar.

Key Points

• The ability of Streptococcus mutans to attach to the tooth surface and contribute to tooth decay is primarily due to their ability to produce a slime layer composed of polysaccharides.
• This slime layer is often referred to as an extracellular polysaccharide matrix or biofilm.
• The production of this biofilm helps the bacteria adhere to the tooth surface and form dental plaque.
• The production of the slime layer is not explicitly mentioned, but it is associated with the metabolism of sugars.

Additional Information

• When the pH of the mouth drops below 5.5, tooth decay begins.
• Tooth enamel, made up of calcium phosphate, is the hardest substance in the body.
• It does not dissolve in water but gets destroyed in the mouth when the pH is below 5.5.
• Bacteria present in the mouth produce acid by breaking down the sugar and food particles left in the mouth after eating.

The correct answer is One gamete fuses with the egg cell and the other one fuses with a diploid secondary nucleus.

Key Points

• In angiosperms, the two male gametes produced by pollen germination have specialized functions during double fertilization.
• One of the male gametes fuses with the egg cell, resulting in the formation of a diploid zygote, which will develop into an embryo.
• The second male gamete fuses with a diploid secondary nucleus (also called a central cell or polar nucleus) to form a triploid cell.
• This triploid cell gives rise to the endosperm, which provides nutrition to the developing embryo.

Additional Information

• Double fertilization includes syngamy and triple fusion.
• In syngamy, the male gamete combines with the female gamete to form a zygote which develops into an embryo.
• In triploid fusion, the male gamete combines with the diploid secondary nucleus to form a triploid primary endosperm nucleus (PEN) which divides to form endosperm.

The correct answer is Both chromosome number and DNA content remain constant.

Key Points

• During sexual reproduction, gametes (sperm and egg cells) are produced through a process called meiosis.
• Meiosis involves a reduction in chromosome number, but each chromosome still contains the same amount of DNA.
• When these gametes fuse during fertilization, the diploid chromosome number is restored in the zygote.
• Therefore, both the chromosome number and DNA content remain constant when considering the parent and offspring in sexually reproducing organisms.

Additional Information

• Chromosomes are a collection of thread-like structures that come in different lengths and forms.
• DNA and proteins (mainly histones) make up chromosomes.
• Genes are carried on chromosomes.
• They are located in the nucleus of eukaryotic cells.
• Chromosomes in humans can be divided into autosomes and sex chromosomes.
• Humans have 22 pairs of autosomes and one pair of sex chromosomes.

The correct answer is Pollination.

Key Points

• Pollination is the process by which pollen grains (male gametes) from the anther of a flower are transferred to the stigma (female reproductive organ) of the same or another flower, leading to fertilization and the production of seeds.
• Ways of Pollination:
• By Wind (Anemophily):
• Some plants produce lightweight and small pollen grains adapted for wind transport.
• Examples include grasses and many trees. Wind pollination is common in areas with a scarcity of pollinating insects.
• By Animals (Zoophily):
• Insects, birds, bats, and other animals are common pollinators.
• Bees, butterflies, moths, hummingbirds, and bats are among the most effective pollinators.
• Flowers attract these animals through colors, scents, and nectar.
• By Water (Hydrophily):
• In aquatic plants, pollen is transported through water.
• This is relatively rare and is adapted to environments like ponds and lakes.

Additional Information

• Types of Pollination:
• Self-Pollination:
• Pollen is transferred from the anther to the stigma of the same flower or another flower on the same plant.
• It ensures reproduction but limits genetic diversity.
• Cross-Pollination:
• Pollen is transferred from the anther of a flower on one plant to the stigma of a flower on another plant of the same species.
• Promotes genetic diversity and is often facilitated by external agents like wind or animals.
• Role of Honeybees:
• Bees play a crucial role in pollination as they collect nectar for their food.
• While collecting nectar, pollen from the anther sticks to their body.
• When they visit another flower, some of this pollen is transferred to the stigma, facilitating fertilization.

The correct answer is Imposing High Taxes.

Key Points

• In ancient India, kings employed various strategies to establish and assert their elevated status. 
• Identifying with a variety of deities:
• Kings often sought to align themselves with divine figures, associating their rule with divine legitimacy.
• This practice aimed to reinforce the idea that the ruler was divinely ordained, enhancing their prestige and authority.
• Assuming pompous titles:
• Kings frequently adopted grandiose titles that emphasized their power and authority.
• These titles often reflected not only political dominance but also conveyed a sense of divine or heroic attributes, contributing to the king's elevated status.
• Imposing high taxes:
• Imposing high taxes was a means of resource mobilization for the state, funding the king's administration, military, and infrastructure projects.
• However, while taxes were a practical necessity, they were not a direct method for claiming a higher status. Instead, they were more associated with the economic functioning of the state.
• Conquests and annexation of territories:
• Kings engaged in military conquests to expand their realms, demonstrating military prowess and territorial control.
• Annexation of territories was a way to assert dominance and increase the king's sphere of influence, showcasing their ability to subjugate rival rulers.

The correct answer is The Bhakti movement avoided traditions that promoted diversity.

Key Points

• The Bhakti Movement was a medieval Indian socio-religious movement that emerged around the 7^th-8^th centuries and continued until the 17^th century.
• Origin and Meaning:
• The term "Bhakti" refers to devotion or intense love towards a personal god.
• The movement originated as a reaction against the ritualistic practices and social hierarchies within Hinduism.
• Key Features:
• Emphasis on a personal relationship with the divine rather than ritualistic observances.
• Inclusivity, breaking down caste and gender barriers.
• Use of vernacular languages to communicate religious ideas, making it accessible to the masses.
• Stress on the equality of all devotees in the eyes of God.
• Prominent Bhakti Saints:
• Ramanuja: Founded the Vishishtadvaita school of Vedanta, emphasizing qualified non-dualism.
• Kabir: Critiqued both Hindu and Islamic rituals, advocating direct devotion to the formless, attribute-less Divine.
• Mirabai: Known for her devotional poetry dedicated to Lord Krishna.
• Sant Tukaram: A Marathi saint who composed abhangas (devotional songs).
• Spread of Bhakti Movement:
• Spread across different regions of India, gaining popularity in Maharashtra, Bengal, Punjab, and the Deccan.
• Integration of Bhakti ideas with Sufi mysticism in certain areas.
• Impact:
• Social reform by challenging the caste system and promoting social equality.
• Cultural impact through devotional literature, poetry, and music.
• Formation of new sects and communities centered around Bhakti ideals.
• Challenges to the Bhakti Movement:
• Opposition from orthodox elements within both Hinduism and Islam.
• Attempts by rulers to suppress movements challenging established social norms.
• Legacy:
• The Bhakti Movement laid the foundation for a more personalized and inclusive approach to spirituality in India.
• Its influence can still be seen in various devotional practices and cultural expressions across the country.
• Alvars:
• The Alvars were a group of Tamil poet-saints who lived between the 6^th and 9^th centuries.
• Composed devotional hymns in praise of Lord Vishnu, contributing to the Bhakti tradition in South India.
• Nammalvar, Andal, and Periyalvar are some of the prominent Alvars.
• Their hymns, known as "Divya Prabandham," emphasized the emotional and devotional aspects of worship.
• Nayanars:
• The Nayanars were devotees of Lord Shiva who played a crucial role in the Bhakti Movement in South India.
• They lived between the 6^th and 9^th centuries.
• Composed devotional hymns known as "Tirumurai" expressing intense love and devotion to Lord Shiva.
• Some notable Nayanars include Appar, Sundarar, and Manickavacakar.
• The Nayanars focused on the idea of surrendering to Shiva and experiencing divine grace.

Additional Information

• The Bhakti and Sufi movements, emerging during medieval times, were significant religious reforms emphasizing fervent devotion to God beyond ritualistic practices.
• Bhakti, rooted in Vedas, was advanced by Shaiva Nayanars and Vaishnavite Alwars in South India, later spreading widely.
• Meanwhile, Sufism, a mystical facet of Islam, started around the 12^th century in Persia and reached India by the 14^th century.
• Bhakti Movement Highlights:
• Originating from the Vedas, Bhakti stressed love and worship in the relationship between humans and God.
• Bhakti saints, divided into Nirgun and Sagun categories, condemned rituals, idol worship, and advocated surrender to God.
• Influenced by Vaishnavism, Sufi sects, and social concerns, Bhakti emerged as a reformative force challenging the caste system.
• Sufi Movement Highlights:
• Sufism, originating from asceticism in Persia, became a mystical aspect of Islam emphasizing love and devotion.
• The movement introduced essential concepts like Fana (spiritual merger), Insan-e-kamil (perfect human), and Wahdat-ul-wajood (unity of being).
• Three historical stages - Khanqah, Tariqa, and Tarifa - marked the institutionalization and popularization of Sufism.
• Sufism encouraged music and poetry, contributing to the evolution of classical music, with notable figures like Amir Khusrau.
• The rejection of elaborate rituals, promotion of devotion over fasts, and discarding caste distinctions were prominent features.
• Sufi orders like Chistis, Suhrawardis, Qadiriyahs, and Naqshbandis played a crucial role in spreading Sufism across India.

The correct answer is 3.

Key Points

• The 'Reign of Terror' in revolutionary France referred to:
• 3. Trial and beheading persons considered enemies of the republic by the revolutionary tribunal
• During the Reign of Terror (1793-1794), the Committee of Public Safety, led by Maximilien Robespierre, wielded immense power. The revolutionary tribunal conducted speedy trials, and many perceived as enemies of the republic were executed by guillotine.
• It was a period marked by political violence, mass executions, and the suppression of perceived counter-revolutionaries.

Additional Information

• The 'Reign of Terror' in revolutionary France (1793-1794) was a period marked by intense political violence and mass executions.
• Background:
• French Revolution Context: The Reign of Terror occurred during the broader French Revolution, a period of radical social and political change.
• Key Aspects of the Reign of Terror:
• Committee of Public Safety: The Committee, led by Maximilien Robespierre, was established to deal with the external and internal threats to the revolution.
• Threats to the Revolution: The revolutionary leaders faced internal challenges from counter-revolutionaries and external threats from monarchies that opposed the revolutionary ideals.
• Revolutionary Tribunal: The Committee established the Revolutionary Tribunal to conduct trials of those accused of being enemies of the republic.
• Swift Justice: Trials were conducted quickly, and the accused were often presumed guilty. The standard of evidence was often low, leading to widespread and arbitrary executions.
• Guillotine Executions: The guillotine became the symbol of the Reign of Terror. Thousands of people, including King Louis XVI and Queen Marie Antoinette, were executed by this method.
• De-Christianization: The revolutionaries pursued radical measures, including the de-Christianization of society, attempting to replace religious traditions with new revolutionary ones.

The correct answer is 3.

Key Points

• These events represent a condensed overview of the freedom struggle, characterized by the sacrifices and efforts of numerous leaders and ordinary citizens who contributed to India's independence.
• This statement does not accurately reflect the impact of the First World War on Europe.
• In fact, the war led to an increase in support for conservative forces and authoritarian regimes in some cases. The destabilizing effects of the war contributed to the rise of dictatorial regimes, such as in Germany with the rise of Adolf Hitler.

Additional Information

• The First World War, spanning from 1914 to 1918, had a profound impact on Europe in various ways:
• From a continent of creditors to debtors:
• Before the war, Europe was economically prosperous, with several nations acting as creditors.
• However, the immense cost of the war led to unprecedented levels of debt for many European nations. The war significantly strained economies and left many nations in financial distress.
• Soldiers placed higher in social status than civilians:
• The war disrupted traditional social structures. Soldiers who fought in the war were often hailed as heroes upon their return, and their sacrifices were recognized.
• This, in some cases, led to a temporary elevation of social status for those who served, but it also brought about challenges as soldiers struggled with the physical and psychological scars of war.
• Popular support for conservative dictatorship:
• Contrary to the statement, the aftermath of World War I witnessed a decline in support for conservative forces in some countries.
• The war had brought about significant social and political changes, leading to discontent with existing conservative regimes.
• In countries like Germany and Russia, the war contributed to the downfall of monarchies and conservative governments.
• National honour in the public sphere:
• The war instilled a sense of nationalism and national pride. Countries, especially those that emerged victorious, celebrated their perceived national honour and achievements during the war.
• However, this sentiment also fueled post-war tensions and contributed to geopolitical shifts, setting the stage for future conflicts..
• Here are key aspects of World War I:
• 1. Causes:
• Imperialism: Rivalries over colonies and territories.
• Nationalism: Intense national pride and competition.
• Militarism: Arms race and military build-up.
• Alliance System: Entangling alliances divided Europe.
• 2. Assassination of Archduke Franz Ferdinand:
• The assassination on June 28, 1914, in Sarajevo triggered the war.
• 3. Central Powers vs. Allies:
• Central Powers: Germany, Austria-Hungary, Ottoman Empire.
• Allies: France, Russia, United Kingdom, later joined by others.
• 4. Trench Warfare:
• Stalemate on the Western Front led to trench warfare.
• Brutal conditions, diseases, and massive casualties.
• 5. New Technologies:
• Introduction of machine guns, tanks, poison gas, and airplanes.
• 6. U.S. Entry:
• Initially neutral, the United States entered in 1917 on the side of the Allies.
• 7. Russian Revolution:
• 1917 revolution led to the Bolshevik takeover and Russia's exit from the war.
• 8. Treaty of Versailles:
• 1919 peace treaty that officially ended the war.
• Imposed harsh terms on Germany, contributing to future conflicts.
• 9. Human Cost:
• Approximately 10 million military personnel and 7 million civilians died.
• 10. Legacy:
• Redrew the map of Europe.
• Set the stage for World War II.
• Marked by the League of Nations' establishment (predecessor to the United Nations).

The correct answer is Quit India Movement.

Key Points

• Certainly, the freedom struggle of India was a prolonged and multifaceted movement against British colonial rule, marked by numerous significant events.
• First War of Independence (1857-1858): Also known as the Sepoy Mutiny or the Indian Rebellion, it was a widespread uprising against the British East India Company. Although it did not succeed in ending British rule, it laid the groundwork for future movements.
• Formation of Indian National Congress (1885): The Indian National Congress (INC) was established, becoming a significant political platform advocating for a greater share in governance for Indians.
• Partition of Bengal (1905): Lord Curzon's decision to partition Bengal along religious lines was met with strong opposition, as it was seen as an attempt to divide Hindus and Muslims. Protests against the partition gained momentum.
• Swadeshi Movement (1905-1908): Triggered by the partition of Bengal, the Swadeshi Movement aimed at promoting Indian-made goods and boycotting British products. It led to the promotion of indigenous industries.
• Jallianwala Bagh Massacre (1919): British troops, led by General Dyer, fired upon a peaceful gathering in Amritsar, resulting in hundreds of deaths. This brutal incident intensified anti-British sentiments.
• Non-Cooperation Movement (1920-1922): Launched by Mahatma Gandhi, it aimed at non-violently resisting British rule. Indians withdrew support from British institutions, including schools and legislatures.
• Civil Disobedience Movement (1930-1934): Gandhi's Salt March is a notable event of this movement. Indians protested against the British salt monopoly by making salt from seawater, symbolizing defiance of the salt tax.
• World War II and Quit India Movement (1942): During WWII, Indians participated, expecting political concessions in return. When the British failed to fulfill promises, the Quit India Movement was launched, demanding an end to British rule.
• Formation of INA (1942-1945): The Indian National Army, led by Subhas Chandra Bose, sought to free India from British rule with the help of Axis powers. Though it didn't succeed militarily, it had a psychological impact.
• Post-War Period and Independence (1945-1947): The naval mutiny of 1946, communal riots, and the realization of British weakness after WWII pressured Britain to grant independence. India gained independence on August 15, 1947, and was partitioned into India and Pakistan.

The correct answer is Kudremukh : Bauxite.

Key Points

• Bailadila: Iron Ore
• Correct: Bailadila is a well-known mining region in Chhattisgarh, India, and it is primarily associated with the extraction of high-grade iron ore.
• Zawar: Zinc
• Correct: Zawar is a historic mining region in Rajasthan, India, known for its lead and zinc mines. Zinc is one of the major minerals extracted from the Zawar mines.
• Ghatsila: Copper
• Correct: Ghatsila is a mining region in Jharkhand, India, and it is associated with the extraction of copper.
• Kudremukh: Bauxite
• Incorrect: Kudremukh is known for its iron ore deposits, not bauxite. The mining activities in Kudremukh are mainly focused on extracting iron ore.
• Therefore, the pair that is NOT correctly matched is Kudremukh: Bauxite​

Additional Information

• Here is information about some other major mineral mines in India, along with the states where they are located:
• Iron Ore Mines:
• Bellary-Hospet Region: Karnataka
• Dalli-Rajhara: Chhattisgarh
• Mayurbhanj: Odisha
• Copper Mines:
• Malanjkhand: Madhya Pradesh
• Singhbhum Copper Belt: Jharkhand and Odisha
• Bauxite Mines:
• Panchpatmali: Odisha
• Niyamgiri Hills: Odisha
• Lead and Zinc Mines:
• Dariba: Rajasthan
• Agucha: Rajasthan
• Rampura Agucha: Rajasthan
• Gold Mines:
• Kolar Gold Fields: Karnataka
• Manganese Mines:
• Balaghat: Madhya Pradesh
• Sandur: Karnataka
• Limestone Mines:
• Satna: Madhya Pradesh
• Jaisalmer: Rajasthan
• Coal Mines:
• Jharia: Jharkhand
• Singrauli: Madhya Pradesh and Uttar Pradesh
• Chromite Mines:
• Sukinda Valley: Odisha
• Uranium Mines:
• Jaduguda: Jharkhand
• Tummalapalle: Andhra Pradesh

The correct answer is Millibar.

Key Points

• The usual unit of measurement for air pressure used in India is Millibar. 
• Centimeter: Centimeter is a unit of length and not used for measuring air pressure.
• Millibar: Millibar (mb) is the standard unit for measuring atmospheric pressure. In the context of weather and atmospheric conditions, millibars are commonly used globally. It's the preferred unit for expressing air pressure in meteorology, including in India.
• Milligram: Milligram is a unit of mass and is not applicable to measuring air pressure.
• Milliliter: Milliliter is a unit of volume and is not relevant for measuring air pressure.
• Pressure is defined as the force exerted per unit area. It is a measure of how much force is applied over a given area.
• The formula for pressure (p) is given by : P=F/A; where P is Pressure, F is force and A is area over which force is applied.
• The SI (International System of Units) unit of pressure is the Pascal (Pa), which is equivalent to one Newton per square meter (N/m^2).
• Other Units of Pressure:
• Atmosphere (atm): Standard atmospheric pressure at sea level is defined as 1 atmosphere. It is approximately equal to 101325 Pascals.
• Bar (bar): Another unit of pressure, equal to 100,000 Pascals.
• Millimeter of Mercury (mmHg) or Torr: Commonly used in measuring atmospheric pressure where 1 mmHg is approximately equal to 133.322 Pa.

The correct answer is Precambrian. 

Key Points

• The oldest era in Geological History is the Precambrian. This era extends from the formation of Earth around 4.6 billion years ago to the beginning of the Cambrian Period, approximately 541 million years ago.
• The Precambrian is divided into three eons: the Hadean, Archean, and Proterozoic.
• Hadean Eon (4.6 - 4.0 billion years ago): This eon corresponds to the early stages of Earth's formation, characterized by intense heat, frequent collisions with celestial bodies, and the gradual cooling of the Earth's surface.
• Archean Eon (4.0 - 2.5 billion years ago): During this eon, the Earth's crust began to solidify, and the first continents and oceans formed. Primitive life forms, such as bacteria and archaea, appeared in the latter part of the Archean.
• Proterozoic Eon (2.5 billion - 541 million years ago): This eon is marked by the emergence of more complex life forms, including multicellular organisms. Oxygen levels in the atmosphere increased due to photosynthetic processes carried out by cyanobacteria. Towards the end of the Proterozoic, the first complex animals evolved.
• The Precambrian sets the stage for the subsequent geological eras, providing the foundation for the diverse life forms that would flourish in the Paleozoic, Mesozoic, and Cenozoic eras.
• It represents an immense span of time, encompassing the majority of Earth's history before the explosion of complex life during the Cambrian Period.

The correct answer is Both 1 and 2.

Key Points

• Lines of Latitude:
• These are the lines that run east to west around the globe.
• They are horizontal lines and measure the distance north or south from the equator.
• Latitude is expressed in degrees. The equator is the reference line with 0° latitude, and the lines are numberedup to 90° N (north of the equator) and 90° S (south of the equator).
• Lines of Longitude:
• These are the lines that run north to south from the North Pole to the South Pole.
• They are vertical lines and measure the distance east or west from the Prime Meridian.
• Longitude is also expressed in degrees.
• The Prime Meridian is the reference line with 0° longitude, and the lines are numbered up to 180° E (east of the Prime Meridian) and 180° W (west of the Prime Meridian).
• The equator is the main reference line with 0° latitude.

Additional Information

• Lines of Latitude:
• There are a total of 90 latitudinal lines in the northern hemisphere, numbered from 0° to 90° N.
• Similarly, there are 90 latitudinal lines in the southern hemisphere, numbered from 0° to 90° S.
• The North Pole is at 90° N, and the South Pole is at 90° S.
• So, there are a total of
• 90+90
• 90+90 latitudinal lines, including the equator.
• Lines of Longitude:
• The Prime Meridian is the main reference line with 0° longitude.
• There are a total of 180 longitudinal lines to the east of the Prime Meridian, numbered from 0° to 180° E.
• Similarly, there are 180 longitudinal lines to the west of the Prime Meridian, numbered from 0° to 180° W.
• So, there are a total of
• 180+180
• 180+180 longitudinal lines, including the Prime Meridian.

The correct answer is Troposphere.

Key Points

• Troposphere is the lowest layer of the atmosphere.
• It has an average altitude of 13 km and extends to a height of about 8 km near the poles and about 18 km at the equator.
• The thickness of the troposphere is greatest at the equator because heat is carried to great heights by strong convection currents.
• This layer contains dust particles and water vapor.
• All changes in climate and weather occur in this layer.
• It is the most important layer for all biological activities.
• The region separating the troposphere from the stratosphere is known as the tropopause.
• The temperature here remains almost constant, hence it is called tropopause.

Additional Information

• Stratosphere
• It is found above the tropopause and extends up to a height of 50 km.
• An important feature of the stratosphere is that it contains the ozone layer.
• This layer absorbs ultraviolet radiation and protects life on Earth from intense, harmful forms of energy.
• Mesosphere
• It is located above the stratosphere, extending up to a height of 80 km.
• In this layer, the temperature once again starts decreasing with increasing altitude and reaches zero to 100°C at an altitude of 80 km.
• The upper limit of the mesosphere is known as the mesopause.
• Thermosphere 
• It is located 80 to 400 km above the mesopause.
• It consists of electrically charged particles called ions, and hence, it is also known as the ionosphere.
• Radio waves transmitted from the Earth are reflected back to the Earth through this layer.
• The temperature here starts increasing with altitude.
• Exosphere
• This is the uppermost layer of the atmosphere.
• This is the highest layer but very little is known about it.
• Whatever materials there are, they are extremely rare in this layer and gradually dissolve into outer space.

The correct answer is Uttarakhand.

Key Points

• Roopkund is a high altitude glacial lake in the Indian state of Uttarakhand.
• It is situated in the lap of Trishul Mountain.
• Located in the Himalayas, the area around the lake is desolate, surrounded by rocky glaciers and snow-capped mountains.

Additional Information

• Uttarakhand was formed as the 27^th state of India on 9 November 2000, when it was carved out of northern Uttar Pradesh.
• It is located in the foothills of the Himalayan mountain range, it is predominantly a mountainous state, with international borders with China (Tibet) in the north and Nepal in the east.
• To its northwest lies Himachal Pradesh, while to the south lies Uttar Pradesh.
• The four most sacred and revered Hindu temples of Char Dham, Badrinath, Kedarnath, Gangotri and Yamunotri are located in the towering mountains.

The correct answer is 50 km/h.

Key Points

• To calculate the average speed, you can use the formula:
• Average Speed $= {Total :Distance\over Total :Time}$
• In this case, the total distance covered is the difference in odometer readings, which is 2400 km − 2000 km = 400 km
• The total time is given as 8 hours
• Average Speed = 400 km/8 hours
• Average Speed = 50 km/h
• Therefore, the average speed of Ram's car is 50 km/h.

The correct answer is A split-ring type commutator.

Key Points

• To convert an AC (alternating current) generator to a DC (direct current) generator, a device called a commutator needs to be connected.
• The commutator is a rotary switch that reverses the direction of current in the coil windings of the generator, thereby converting AC to DC.
• Split ring commutator:
• A slip-ring commutator simply establishes a connection or contact between the rotating rotor and the fixed stator, but a split-ring commutator causes the current to change direction every alternate half-rotation.
• Because the current direction changes every half-rotation and the split ring commutator reverses the current trajectory for every alternate half-revolution, it changes the current state to positive every half-cycle.
• The rotor coil is connected to the split ring commutator (armature). The armature is often composed of several coils of insulated wire wrapped around an iron core, with each termination point connected to one side of the commutator. Current flows in it, which interacts with the magnetic field to produce torque.
• AC to DC generator: An alternating current generator is a mechanical device that converts mechanical energy into alternating current electrical power.

Additional Information

• Slip rings and brushes: The main function of these slip rings is to transmit electrical power to a coil that is at rest to move or rotate it specifically. A carbon brush is attached to the slip ring. It helps in transmitting the electric current received from the slip ring further in the circuit.
• A stronger magnetic field: Magnetic lines being close to each other means a strong magnetic field and lines being far from each other means a weak magnetic field. The magnetic field is strongest at the poles of a magnet, so the lines at the poles are close to each other.

The correct answer is - 0.5 D.

Key Points

• When a person is unable to clearly see objects placed at a distance of more than 2 m, he is suffering from myopia.
• In this condition, the person is not able to see the objects kept far away, but can see the objects kept near clearly and this condition is called myopia.
• The required Power of the lens is given by
• $P = {1 \over f}$
• $P = {-1 \over 2} = {-0.5:D}$
• This defect can be corrected by using a concave lens of power -0.5 D.
• Nearsightedness occurs when the lens of the eye becomes unable to converge the rays because the rays come from a very short distance and thus it becomes more difficult to diffuse those rays compared to distant rays.
• The power of the lens is measured in the SI unit Dioptre.

Additional Information

• Myopia is commonly known as nearsightedness.
• In this condition the person can see nearby objects but is not able to see distant objects clearly.
• Myopia occurs when the shape of the eye bends light rays incorrectly, causing the image to be focused in front of the retina instead of on the retina.
• When a concave lens of appropriate power is used, it helps focus the image on the retina.
• Hypermetropia is commonly known as far-sightedness.
• In this condition the person can see distant objects but is not able to see nearby objects clearly.
• Hypermetropia occurs when light rays from a nearby object focus on a point behind the retina.
• Using glasses with converging lenses provides additional focusing power and thus helps form the image on the retina.

The correct answer is 2 and 3.

Key Points

• Resistance depends inversely on the area, not directly. Resistivity directly depends on the area of the cross-section of the wire. Hence, statement 1 is incorrect.
• The electrical resistance of a wire generally increases with temperature. This phenomenon is described by the temperature coefficient of resistance. Hence, statement 2 is correct.
• The resistance (R) is directly proportional to the resistivity (ρ) and the length (L), and inversely proportional to the cross-sectional area (A), as mentioned in the formula R = ρL/A. Hence, statement 3 is correct.
• The resistivity of the wire is inversely proportional to the length of the wire. Hence, statement 4 is incorrect.

Additional Information

• Resistance:
• The property of any conductor which opposes the flow of electric current through it is called resistance.
• It is represented by R and the SI unit is Ohm (Ω).
• The resistance of a metallic wire is directly proportional to its length and inversely proportional to the area of its cross-section.
• The resistance (R) is given by:
• R = ρL / A
• where ρ is resistivity, L is the length and A is the area of the cross-section.
• Effect of Temperature on Resistance:
• For pure metals, resistance increases with an increase in temperature, this is called the positive temperature coefficient of resistance.
• For semiconductors and insulators, resistance increases with a decrease in temperature and vice versa, this is called negative temperature coefficient of resistance.