UPSC Prelims PYQs with explanations
Real questions from official papers, mapped to syllabus topics. Attempt each one; the answer and the reason appear instantly.
Read the passage
The poor especially in market economies, need the strength that collectivities offer for creating more economic, social and political space for themselves, for enhancing their socio-economic well-being and voice, and as a protection against free market individualism. It has been argued that a group approach to farming, especially in the form of bottom up agricultural production collectivities, offers substantial scope for poverty alleviation and empowering the poor as well as enhancing agricultural productivity. To realise this potential, however, the groups would need to be voluntary in nature, small in size, participative in decision making and equitable in work sharing and benefit distribution. There are many notable examples of such collectivities to be found in varied contexts, such as in the transition economies. All of them bear witness to the possibility of successful cooperation under given conditions. And although the gender impact of the family cooperatives in the transition economies are uncertain, the Indian examples of women-only groups farming offer considerable potential for benefiting women.
What does the author imply by “gender impact” ?
Answer (c) & explanation
(c) is correct. Step 1: 'gender impact' means the effect on women (and men). The passage says the gender impact of family cooperatives in transition economies is uncertain, but the Indian women-only groups 'offer considerable potential for benefiting women'. So the author is talking about women benefiting from group farming. Step 2: (a) and (b) are wrong: the passage never says women are doubtful participants or that family cooperatives leave women out. Step 3: (d) is wrong: nothing says women's role in transition economies is highly restrictive; the impact there is only 'uncertain'. So (a), (b) and (d) fail.
Tip: 'impact' asks about effects. Pick the option that names an effect the passage mentions.
Answer as per the official UPSC answer key.
If National Water Mission is properly and completely implemented, how will it impact the country?
- 1. Part of the water needs of urban areas will be met through recycling of waste-water.
- 2. The water requirements of coastal cities with inadequate alternative sources of water will be met by adopting appropriate technologies that allow for the use of ocean water.
- 3. All the rivers of Himalayan origin will be linked to the rivers of peninsular India.
- 4. The expenses incurred by farmers for digging bore-wells and for installing motors and pump-sets to draw ground-water will be completely reimbursed by the Government.
Select the correct answer using the codes given below :
Answer (b) & explanation
Statements 1 and 2 are correct (b). The National Water Mission is one of the eight missions of the National Action Plan on Climate Change (2008). It aims to raise water-use efficiency by 20%, including recycling of waste water in cities (1) and desalination and other technologies for coastal cities short of water (2). Statement 3 is wrong: interlinking of rivers is a separate programme, not part of the mission. Statement 4 is wrong: the mission does not reimburse farmers' bore-well and pump costs; it seeks to curb groundwater overuse. So (a), (c) and (d) fail.
Notice the related schemes: Atal Bhujal Yojana (2019) for groundwater, Jal Shakti Abhiyan: Catch the Rain, and the Ken–Betwa link, the first project under the national river-linking plan.
Answer as per the official UPSC answer key.
Consider the following specific stages of demographic transition associated with economic development :
- 1. Low birthrate with low death rate
- 2. High birthrate with high death rate
- 3. High birthrate with low death rate
Select the correct order of the above stages using the codes given below :
Answer (c) & explanation
The order 2, 3, 1 is correct (c). In the demographic transition model, poor agrarian societies start with high birth and high death rates, so population grows slowly (2). Better food, medicine and sanitation bring the death rate down while births stay high, causing a population boom (3). Finally education, urbanisation and women's empowerment bring births down too, giving low birth and low death rates (1). So (a), (b) and (d) give the wrong order.
Notice India's stage: India's TFR fell to 2.0 in NFHS-5, below replacement (2.1), so it is entering the late stage, with a demographic dividend until about the 2040s. Some models add a fifth stage where births fall below deaths, as in Japan. Trap: the list deliberately starts with the final stage.
Answer as per the official UPSC answer key.
The Lahore Session of the Indian National Congress (1929) is very important in history, because
- 1. the Congress passed a resolution demanding complete independence
- 2. the rift between the extremists and moderates was resolved in that Session
- 3. a resolution was passed rejecting the two-nation theory in that Session
Which of the statements given above is/are correct?
Answer (a) & explanation
Statement 1 only is correct (a). At the Lahore session (December 1929), presided over by Jawaharlal Nehru, the Congress passed the Purna Swaraj (complete independence) resolution (1), hoisted the tricolour on the banks of the Ravi, and fixed 26 January 1930 as Independence Day. Statement 2 is wrong: the moderate–extremist rift was healed at Lucknow in 1916. Statement 3 is wrong: the two-nation theory was not on the agenda in 1929. So (b), (c) and (d) fail.
Notice the follow-up: the session authorised civil disobedience, which began with the Dandi March (12 March 1930). The Constitution came into force on 26 January 1950 to honour that date. Trap: 1916 Lucknow is famous for two unities: Congress factions and the Congress–League pact.
Answer as per the official UPSC answer key.
Which of the following statements is/are correct regarding Brahmo Samaj?
- 1. It opposed idolatry.
- 2. It denied the need for a priestly class for interpreting the religious texts.
- 3. It popularized the doctrine that the Vedas are infallible.
Select the correct answer using the codes given below :
Answer (b) & explanation
Statements 1 and 2 are correct (b). Raja Rammohan Roy's Brahmo Samaj (founded as Brahmo Sabha in 1828) preached one formless God, opposed idolatry (1), and rejected the need for priests to interpret scriptures (2). Statement 3 is wrong: under Debendranath Tagore, the Brahmo Samaj formally rejected the infallibility of the Vedas. 'Back to the Vedas' and their infallibility was the Arya Samaj line of Dayanand Saraswati (1875). So (a), (c) and (d) fail.
Notice the splits: Keshab Chandra Sen formed the Brahmo Samaj of India (1866), and the Sadharan Brahmo Samaj broke away in 1878 after Keshab married his minor daughter to the Cooch Behar prince. Rammohan also fought for the abolition of sati (1829). Trap: two reform societies are mixed up.
Answer as per the official UPSC answer key.
Read the passage
Invasions of exotic species into new geographic areas sometimes occur naturally and without human agency. However, human actions have increased this trickle to a flood. Human-caused introductions may occur either accidentally as a consequence of human transport, or intentionally but illegally to serve some private purpose or legitimately to procure some hoped-for public benefit by bringing a pest under control, producing new agricultural products or providing novel recreational opportunities. Many introduced species are assimilated into communities without much obvious effect. However, some have been responsible for dramatic changes to native species and natural communities. For example, the accidental introduction of the brown tree snake Boiga irregularis into Guam, an island in the Pacific, has through nest predation reduced 10 endemic forest bird species to the point of extinction.
One of the major reasons for the world’s great biodiversity is the occurrence of centers of endemism so that similar habitats in different parts of the world are occupied by different groups of species that happen to have evolved there. If every species naturally had access to everywhere on the globe, we might expect a relatively small number of successful species to become dominant in each biome. The extent to which this homogenization can happen naturally is restricted by the limited powers of dispersal of most species in the face of the physical barriers that exist to dispersal. By virtue of the transport opportunities offered by humans, these barriers have been breached by an ever-increasing number of exotic species. The effects of introductions have been to convert a hugely diverse range of local community compositions into something much more homogeneous.
It would be wrong, however, to conclude that introducing species to a region will inevitably cause a decline in species richness there. For example, there are numerous species of plants, invertebrates and vertebrates found in continental Europe but absent from the British Isles (many because they have so far failed to recolonize after the last glaciations). Their introduction would be likely to augment British biodiversity. The significant detrimental effect noted above arises where aggressive species provide a novel challenge to endemic biotas ill-equipped to deal with them.
How have the human beings influenced the biodiversity ?
- 1. By smuggling live organisms.
- 2. By building highways.
- 3. By making ecosystems sensitive so that new species are not allowed.
- 4. By ensuring that new species do not have major impact on local species.
Which of the statements given above are correct ?
Answer (a) & explanation
1 and 2 are correct (a). Step 1: the passage says introductions may be 'intentionally but illegally' made for private purposes, which matches smuggling live organisms (1). Step 2: it says 'transport opportunities offered by humans' have breached natural barriers. Highways are such transport routes (2). Step 3: statements 3 and 4 claim humans protect ecosystems from new species. The passage says the opposite: humans turned 'this trickle to a flood' and caused dramatic harm, as on Guam. So 3 and 4 are wrong, and (b), (c) and (d) fail.
Tip: check the direction of the passage. Here humans are blamed for spreading species, so options showing humans as protectors go against it.
Answer as per the official UPSC answer key.
Consider the following statements:
- 1. All machines consume energy.
- 2. Electricity provides energy.
- 3. Electrically operated machines are cheap to maintain.
- 4. Electrically operated machines do not cause pollution.
Which one of the following inferences can be drawn from the above statements?
Answer (d) & explanation
(d) is correct. Step 1: statements 3 and 4 give two advantages of electric machines: they are cheap to maintain and do not cause pollution. So electric machines are preferable to use. Step 2: (a) is wrong: statement 1 says all machines use energy, not that all use electricity. (b) is wrong: 'electricity provides energy' does not mean it is the only form of energy. Step 3: (c) is wrong: nothing tells us how many machines run on electricity, so 'most' cannot be inferred. So (a), (b) and (c) fail.
Tip: 'X provides energy' does not mean 'only X provides energy'. Inferences that add 'all', 'only' or 'most' need direct support.
Answer as per the official UPSC answer key.
With reference to ‘stem cells’, frequently in the news, which of the following statements is/are correct?
- 1. Stem cells can be derived from mammals only.
- 2. Stem cells can be used for screening new drugs.
- 3. Stem cells can be used for medical therapies.
Select the correct answer using the codes given below :
Answer (b) & explanation
Statements 2 and 3 are correct (b). Stem cells are unspecialised cells that can divide and turn into other cell types. They are used to grow tissues in the lab to screen new drugs for safety and effect (2), and in therapies such as bone-marrow transplants for leukaemia (3). Statement 1 is wrong: stem cells exist in all multicellular organisms, including plants (meristems), not only mammals. So (a), (c) and (d) fail.
Notice the types: embryonic (pluripotent), adult (multipotent) and induced pluripotent stem cells (iPSCs), for which Shinya Yamanaka shared the 2012 Nobel Prize. India's ICMR guidelines (2017) permit only approved stem-cell therapies, mainly bone-marrow transplants. Trap: 'mammals only' is too narrow.
Answer as per the official UPSC answer key.
Normally, the temperature decreases with the increase in height from the Earth’s surface, because
- 1. the atmosphere can be heated upwards only from the Earth’s surface
- 2. there is more moisture in the upper atmosphere
- 3. the air is less dense in the upper atmosphere
Select the correct answer using the codes given below :
Answer (c) & explanation
Statements 1 and 3 are correct (c). Sunlight passes through the air and heats the ground first; the ground then heats the air from below by radiation, conduction and convection (1). Higher up, the air is thinner, with fewer molecules and less water vapour and CO₂ to absorb and hold heat (3). So temperature falls about 6.5°C per km, the normal lapse rate. Statement 2 is wrong: moisture is greatest near the surface, not higher up. So (a), (b) and (d) fail.
Notice the exceptions: a temperature inversion, common on winter nights and in valleys, traps smog, as in Delhi each winter. In the stratosphere, temperature rises with height because ozone absorbs UV. Trap: statement 2 reverses where water vapour sits.
Answer as per the official UPSC answer key.
A person stood alone in a desert on a dark night and wanted to reach his village which was situated 5 km east of the point where he was standing. He had no instruments to find the direction but he located the polestar. The most convenient way now to reach his village is to walk in the
Answer (c) & explanation
Keeping the pole star to his left is correct (c). The pole star (Polaris) sits almost directly over the North Pole, so it marks north. The village lies to the east. Facing east, north is on your left, so he should walk with the pole star on his left. (a) is wrong: facing the pole star means walking north. (b) is wrong: walking away from it means going south. (d) is wrong: the pole star on the right means walking west.
Notice the related tricks: Polaris is found by following the two 'pointer' stars of the Big Dipper (Saptarishi). Its height above the horizon roughly equals your latitude, which is why it cannot be seen from the southern hemisphere. Trap: confusing left and right when imagining the turn.
Answer as per the official UPSC answer key.
Read the passage
Today’s developing economies use much less energy per capita than developed countries such as the United States did at similar incomes, showing the potential for lower-carbon growth. Adaptation and mitigation need to be integrated into a climate-smart development strategy that increases resilience, reduces the threat of further global warming, and improves development outcomes. Adaptation and mitigation measures can advance development, and prosperity can raise incomes and foster better institutions. A healthier population living in better-built houses and with access to bank loans and social security is better equipped to deal with a changing climate and its consequences. Advancing robust, resilient development policies that promote adaptation is needed today because changes in the climate, already begun, will increase even in the short term.
The spread of economic prosperity has always been intertwined with adaptation to changing ecological conditions. But as growth has altered the environment and as environmental change has accelerated, sustaining growth and adaptability demands greater capacity to understand our environment, generate new adaptive technologies and practices, and diffuse them widely. As economic historians have explained, much of humankind’s creative potential has been directed at adapting to the changing world. But adaptation cannot cope with all the impacts related to climate change, especially as larger changes unfold in the long term.
Countries cannot grow out of harm’s way fast enough to match the changing climate. And some growth strategies, whether driven by the government or the market, can also add to vulnerability — particularly if they overexploit natural resources. Under the Soviet development plan, irrigated cotton cultivation expanded in water-stressed Central Asia and led to the near disappearance of the Aral Sea, threatening the livelihoods of fishermen, herders and farmers. And clearing mangroves — the natural coastal buffers against storm surges — to make way for intensive farming or housing development, increases the physical vulnerability of coastal settlements, whether in Guinea or in Louisiana.
Which of the following conditions of growth can add to vulnerability ?
- 1. When the growth occurs due to excessive exploitation of mineral resources and forests.
- 2. When the growth brings about a change in humankind’s creative potential.
- 3. When the growth is envisaged only for providing houses and social security to the people.
- 4. When the growth occurs due to emphasis on farming only.
Select the correct answer using the codes given below :
Answer (a) & explanation
Only condition 1 is correct (a). Step 1: the passage says some growth strategies 'can also add to vulnerability — particularly if they overexploit natural resources'. Its examples are draining the Aral Sea and clearing mangroves. Overusing minerals and forests fits this: 1 is right. Step 2: condition 2 is wrong: creative potential helps us adapt; it does not add to vulnerability. Condition 3 is wrong: better houses and social security make people better equipped to cope. Step 3: condition 4 is wrong: the problem was intensive farming that overused water, not farming as such. So (b), (c) and (d) fail.
Tip: find the passage's exact cause ('overexploit natural resources') and pick the option that matches it, not one that matches only the example.
Answer as per the official UPSC answer key.
Four political parties W, X, Y and Z decided to set up a joint candidate for the coming parliamentary election. The formula agreed by them was the acceptance of a candidate of the most of the parties. Four aspiring candidates A, B, C and D approached the parties for their tickets. A was acceptable to W but not to Z. B was acceptable to Y but not to X. C was acceptable to W and Y. D was acceptable to W and X. When candidate B was preferred by W and Z, candidate C was preferred by X and Z and candidate A was acceptable to X but not to Y; who got the ticket?
Answer (c) & explanation
C got the ticket (c). Step 1: list who accepts each candidate. A: W, and later X, so 2 parties (Z and Y reject A). B: Y, and later W and Z, so 3 parties (X rejects B). C: W and Y, and later X and Z, so all 4 parties. D: W and X, so 2 parties. Step 2: the formula was the candidate acceptable to most parties. Step 3: C has the most support (4), so C gets the ticket. A and D have 2 each and B has 3, so (a), (b) and (d) fail.
Tip: make a small table of candidates against parties and tick each acceptance as you read. Counting ticks avoids mixing up the later preferences.
Answer as per the official UPSC answer key.
Directions: each item describes a situation and is followed by four possible responses. Indicate the response you find most appropriate. There is no penalty for wrong answers for these items. You have differences of opinion regarding the final report prepared by your subordinate that is to be submitted urgently. The subordinate is justifying the information given in the report. You would...
Answer (a) & explanation
(a) and (c) are both correct (UPSC accepted both; no negative marking). Step 1: the report is urgent and you disagree with it. You need a quick, correct result. Step 2: (a) convincing the subordinate with reasons settles the issue and helps him learn. (c) revising the report yourself ensures it goes out correct and on time. Step 3: (b) sending it back to 'reconsider' wastes time when he is already defending it. (d) simply telling him not to justify the mistake is bossy and solves nothing.
Tip: for these interpersonal items, pick the response that is lawful, honest and fixes the real problem through proper channels. Avoid options that give in, run away from duty or act without hearing the facts.
Answer as per the official UPSC answer key.
During Indian freedom struggle, the National Social Conference was formed. What was the reason for its formation?
Answer (b) & explanation
Option (b) is correct. The early Indian National Congress kept to political questions so as not to divide its members over social customs. So M.G. Ranade and Raghunath Rao set up the Indian National Social Conference in 1887 as a separate forum for social reform, meeting at the same venue as Congress sessions. (a) is wrong: it was an all-India body, not a Bengal union. (c) is partly right on names, since Behramji Malabari campaigned for the Age of Consent Act, but it misses the reason. (d) fails because (b) is correct.
Notice the later clash: in 1895 Tilak's supporters stopped the Social Conference from using the Congress pandal at Poona. Ranade also founded the Prarthana Samaj links and the Deccan Education Society spirit. Trap: (c) names real reformers but not the cause.
Answer as per the official UPSC answer key.
To meet its rapidly growing energy demand, some opine that India should pursue research and development on thorium as the future fuel of nuclear energy. In this context, what advantage does thorium hold over uranium?
- 1. Thorium is far more abundant in nature than uranium.
- 2. On the basis of per unit mass of mined mineral, thorium can generate more energy compared to natural uranium.
- 3. Thorium produces less harmful waste compared to uranium.
Which of the statements given above is/are correct?
Answer (d) & explanation
All three are correct per UPSC's key (d). Thorium is about three to four times more abundant than uranium in the Earth's crust, and India holds about a quarter of world reserves in monazite sands of Kerala, Tamil Nadu and Odisha (1). Nearly all mined thorium-232 can be bred into fissile uranium-233, unlike the 0.7% U-235 in natural uranium, so it can yield more energy per tonne mined (2). The thorium cycle produces far fewer long-lived transuranic wastes such as plutonium (3). So (a), (b) and (c) leave out real advantages.
Notice India's plan: thorium is stage three of Bhabha's three-stage programme; the Prototype Fast Breeder Reactor at Kalpakkam began core loading in 2024. Thorium is not fissile itself, so it needs a starter fuel. Trap: 'more energy' holds only via breeding.
Answer as per the official UPSC answer key.
Which of the following can be threats to the biodiversity of a geographical area?
- 1. Global warming
- 2. Fragmentation of habitat
- 3. Invasion of alien species
- 4. Promotion of vegetarianism
Select the correct answer using the codes given below :
Answer (a) & explanation
Items 1, 2 and 3 are correct (a). The main threats to biodiversity are habitat loss and fragmentation (2), invasive alien species such as Lantana and Prosopis in India (3), climate change (1), pollution and over-exploitation. Item 4 is wrong: vegetarianism needs less land and water than meat-heavy diets, so it reduces pressure on habitats; it is not a threat. So (b), (c) and (d) fail.
Notice the framework: E.O. Wilson's 'HIPPO' (habitat loss, invasive species, pollution, population, over-harvesting). The IPBES assessment (2019) said about 1 million species face extinction. India's National Biodiversity Strategy and Action Plan (2024) aligns with the Kunming-Montreal 30x30 target. Trap: item 4 is a lifestyle choice dressed up as a threat.
Answer as per the official UPSC answer key.
Ten new TV shows started in January — 5 sitcoms, 3 drama and 2 news magazines. By April, only seven of the new shows were still on, five of them being sitcoms. Based on the above information, four conclusions, as given below, have been made. Which one of these logically follows from the information given above?
Answer (c) & explanation
'At least one discontinued show was a drama' is correct (c). Step 1: 10 shows began; 7 were still on, and 5 of those were sitcoms. So all 5 sitcoms survived, and 3 shows were stopped, all from the 3 dramas and 2 news magazines. Step 2: there are only 2 news magazines, so at least one of the 3 stopped shows must be a drama. Step 3: (a) and (b) cannot be fixed; the survivors could be 2 dramas or 1 drama and 1 news show, or 2 news shows. (d) talks about viewers' choices, which the data does not show. So (a), (b) and (d) fail.
Tip: 'at least' answers often come from counting: if 3 items must come from a group where one type has only 2, the other type must appear.
Answer as per the official UPSC answer key.
Read the passage
The poor especially in market economies, need the strength that collectivities offer for creating more economic, social and political space for themselves, for enhancing their socio-economic well-being and voice, and as a protection against free market individualism. It has been argued that a group approach to farming, especially in the form of bottom up agricultural production collectivities, offers substantial scope for poverty alleviation and empowering the poor as well as enhancing agricultural productivity. To realise this potential, however, the groups would need to be voluntary in nature, small in size, participative in decision making and equitable in work sharing and benefit distribution. There are many notable examples of such collectivities to be found in varied contexts, such as in the transition economies. All of them bear witness to the possibility of successful cooperation under given conditions. And although the gender impact of the family cooperatives in the transition economies are uncertain, the Indian examples of women-only groups farming offer considerable potential for benefiting women.
Consider the following assumptions :
- 1. It is imperative for transition economies to have agricultural collectivities.
- 2. Agricultural productivity can be increased by group approach to farming.
With reference to the above passage, which of these assumptions is/are valid ?
Answer (b) & explanation
Only assumption 2 is valid (b). Step 1: the passage says group farming 'offers substantial scope for… enhancing agricultural productivity'. So assumption 2 is valid. Step 2: assumption 1 says collectivities are imperative (a must) for transition economies. The passage only mentions transition economies as places where examples of such groups are found. It never says they must have them. Step 3: so 1 is not valid, and (a), (c) and (d) fail.
Tip: 'imperative', 'must' and 'essential' are strong words. If the passage only gives examples or says something 'can' happen, such strong statements are not valid assumptions. Match the strength of the option to the strength of the text.
Answer as per the official UPSC answer key.
Consider the following provisions under the Directive Principles of State Policy as enshrined in the Constitution of India :
- 1. Securing for citizens of India a uniform civil code
- 2. Organizing village Panchayats
- 3. Promoting cottage industries in rural areas
- 4. Securing for all the workers reasonable leisure and cultural opportunities
Which of the above are the Gandhian Principles that are reflected in the Directive Principles of State Policy?
Answer (b) & explanation
Statements 2 and 3 are correct (b). The Gandhian principles in the Directive Principles include organising village panchayats (Article 40) and promoting cottage industries in rural areas (Article 43), along with prohibition of intoxicants (47), cow protection (48) and the welfare of weaker sections (46). Statement 1 is wrong: the uniform civil code (Article 44) is a liberal-intellectual principle. Statement 4 is wrong: securing workers a living wage, leisure and cultural opportunities (Article 43) is usually counted as a socialist principle. So (a), (c) and (d) fail.
Notice the twist: Article 43 holds both a socialist part (living wage) and a Gandhian part (cottage industries). Uttarakhand enacted the first state UCC in 2024. Trap: one Article can carry two kinds of principle.
Answer as per the official UPSC answer key.
In India, in the overall Index of Industrial Production, the Indices of Eight Core Industries have a combined weight of 37.90%. Which of the following are among those Eight Core Industries?
- 1. Cement
- 2. Fertilizers
- 3. Natural gas
- 4. Refinery products
- 5. Textiles
Select the correct answer using the codes given below :
Answer (c) & explanation
Items 1, 2, 3 and 4 are correct (c). The eight core industries are coal, crude oil, natural gas, refinery products, fertilisers, steel, cement and electricity, so cement (1), fertilisers (2), natural gas (3) and refinery products (4) are included. Item 5 is wrong: textiles is not a core industry. So (a), (b) and (d) fail.
Notice the weights: on the 2011–12 base, the eight cores make up about 40.27% of the IIP; refinery products carry the largest weight (about 28%), followed by electricity and steel, while fertilisers carry the least. The index is released monthly by the Office of the Economic Adviser, DPIIT. Trap: textiles is a big industry but not 'core' infrastructure.
Answer as per the official UPSC answer key.