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 greatest blessing that technological progress has in store for mankind is not, of course, an accumulation of material possessions. The amount of these that can be effectively enjoyed by one individual in one lifetime is not great. But there is not the same narrow limit to the possibilities of the enjoyment of leisure. The gift of leisure may be abused by people who have had no experience of making use of it. Yet the creative use of leisure by a minority in societies has been the mainspring of all human progress beyond the primitive level.
With reference to the above passage, the following assumptions have been made :
- 1. People always see the leisure time as a gift and use it for acquiring more material possessions.
- 2. Use of leisure by some people to produce new and original things has been the chief source of human progress.
Which of these assumptions is/are valid?
Answer (b) & explanation
Only assumption 2 is valid (b). Step 1: the passage says "the creative use of leisure by a minority… has been the mainspring of all human progress". So some people using leisure to create new things drove progress. Assumption 2 holds. Step 2: assumption 1 says people always see leisure as a gift and use it to gain more possessions. But the passage warns leisure "may be abused", and it does not call possessions the blessing. Step 3: so assumption 1 fails, and options (a), (c) and (d) fail.
Tip: "always" in a statement is a warning sign. If the passage admits even one exception, like leisure being abused, "always" is false.
Answer as per the official UPSC answer key.
The outer surface of a 4 cm × 4 cm × 4 cm cube is painted completely in red. It is sliced parallel to the faces to yield sixty four 1 cm × 1 cm × 1 cm small cubes. How many small cubes do not have painted faces?
Answer (a) & explanation
8 small cubes have no painted face (a). Step 1: the 4 × 4 × 4 cube is cut into 64 small cubes. Only the outer layer is painted. Step 2: the unpainted cubes form an inner block. Remove one layer from each side: 4 − 2 = 2 cubes along each edge. Step 3: the inner block is 2 × 2 × 2 = 8 cubes. Option (c), 24, is the number with exactly one painted face. Option (b), 16, and option (d), 36, do not fit.
Tip: for an n × n × n painted cube, unpainted = (n − 2)³, one face = 6(n − 2)², two faces = 12(n − 2), and three faces = 8. Learn these four formulas.
Answer as per the official UPSC answer key.
Which of the following statements is/are correct regarding the Monetary Policy Committee (MPC) ?
- 1. It decides the RBI's benchmark interest rates.
- 2. It is a 12-member body including the Governor of RBI and is reconstituted every year.
- 3. It functions under the chairmanship of the Union Finance Minister.
Select the correct answer using the code given below :
Answer (a) & explanation
Only statement 1 is correct (a). The Monetary Policy Committee, set up in 2016 under the amended RBI Act, 1934 (Section 45ZB), fixes the repo rate to meet the inflation target of 4% ± 2% (1). Statement 2 is wrong because it has six members, not twelve, and it is not reconstituted every year. Three are from the RBI, including the Governor as chair, who has a casting vote. Three outside experts are appointed by the government for four years. Statement 3 is wrong because the Finance Minister has no seat on it.
It meets at least four times a year, usually six. Notice that if inflation stays outside the band for three quarters in a row, the RBI must write to the government explaining why, as it did in 2022.
"12-member" and "Finance Minister". Both are invented; the six-member, Governor-led design keeps it independent.
Answer as per the official UPSC answer key.
The terms ‘Event Horizon’, ‘Singularity’, ‘String Theory’ and ‘Standard Model’ are sometimes seen in the news in the context of
Answer (a) & explanation
These terms are about understanding the Universe (a). An event horizon is the boundary around a black hole from which nothing, not even light, can escape. A singularity is the point of infinite density at its centre, where general relativity breaks down. String theory tries to unify gravity with quantum physics by treating particles as tiny vibrating strings. The Standard Model describes the fundamental particles and three of the four forces, and its last missing piece, the Higgs boson, was found at CERN in 2012. None of this relates to eclipses (b), satellites (c), or the evolution of life (d).
The Event Horizon Telescope photographed black holes in M87 (2019) and Sagittarius A* (2022). Notice the 2020 Nobel Prize for black-hole research (Penrose, Genzel and Ghez).
Answer as per the official UPSC answer key.
What is the application of Somatic Cell Nuclear Transfer Technology ?
Answer (c) & explanation
SCNT is used for reproductive cloning of animals (c). In Somatic Cell Nuclear Transfer, the nucleus of a body (somatic) cell is placed into an egg whose own nucleus has been removed. The egg is then made to divide and grows into a genetic copy of the donor. Dolly the sheep (1996, Roslin Institute) was the first mammal cloned this way. In India, NDRI Karnal cloned the buffalo Garima (2010), and India later cloned a Gir calf and cloned camels in Dubai. SCNT has nothing to do with biolarvicides (a), bioplastics (b), or disease-free organisms (d).
It is also used for therapeutic cloning, to make patient-matched stem cells. Notice the ethics: India bans human reproductive cloning under ICMR guidelines.
Answer as per the official UPSC answer key.
Read the passage
In the last two decades, the world’s gross domestic product (GDP) has increased by 50 per cent, whereas inclusive wealth has increased by a mere 6 per cent. In recent decades, GDP-driven economic performance has only harmed inclusive wealth like human capital; and natural capital like forests, land and water. While the world’s human capital which stands at 57 per cent of total inclusive wealth grew by only 8 per cent, the natural capital which is 23 per cent of total inclusive wealth declined by 30 per cent worldwide in the last two decades.
Which of the following is the most crucial inference from the above passage?
Answer (b) & explanation
The crucial inference is that growth driven by GDP alone is neither desirable nor sustainable (b). Step 1: the passage says GDP rose about 50%, but inclusive wealth rose only 6%, and natural capital fell about 30%. So GDP growth hid a loss of real wealth. Step 2: this means GDP-only growth is not sustainable, which is option (b). Step 3: options (a) and (d) each pick one part of the argument, natural or human capital. Option (c), that world economic performance is unsatisfactory, is too vague.
Tip: inclusive wealth counts natural, human and produced capital together. A rising GDP with falling natural capital means a country is spending its savings.
Answer as per the official UPSC answer key.
There is a milk sample with 50% water in it. If 1/3rd of this milk is added to equal amount of pure milk, then water in the new mixture will fall down to
Answer (a) & explanation
Water in the new mixture falls to 25% (a). Step 1: take 1 litre of the sample. It has 0.5 litre water and 0.5 litre milk. Step 2: add an equal amount, 1 litre, of pure milk. Now there are 2 litres, with still only 0.5 litre of water. Step 3: water = 0.5 ÷ 2 = 25%. The "1/3rd" only says how much of the sample is used. Since an equal amount of pure milk is added, the share is always halved. Options (b), (c) and (d) do not fit.
Tip: mixing a sample with an equal amount of a pure liquid halves the share of the other part. 50% water becomes 25%, whatever the quantity.
the 1/3rd is a distraction. Equal amounts halve the water share.
Answer as per the official UPSC answer key.
A, B, C, D, E, F and G are Lecturers from different cities—Hyderabad, Delhi, Shillong, Kanpur, Chennai, Mumbai and Srinagar (not necessarily in the same order) who participated in a conference. Each one of them is specialized in a different subject, viz., Economics, Commerce, History, Sociology, Geography, Mathematics and Statistics (not necessarily in the same order). Further
- 1. Lecturer from Kanpur is specialized in Geography
- 2. Lecturer D is from Shillong
- 3. Lecturer C from Delhi is specialized in Sociology
- 4. Lecturer B is specialized in neither History nor Mathematics
- 5. Lecturer A who is specialized in Economics does not belong to Hyderabad
- 6. Lecturer F who is specialized in Commerce belongs to Srinagar
- 7. Lecturer G who is specialized in Statistics belongs to Chennai
Who is specialized in Geography?
Answer (a) & explanation
B is specialised in Geography (a). Step 1: clues 3, 5, 6 and 7 fix four subjects: C has Sociology, A Economics, F Commerce and G Statistics. Step 2: the subjects left are History, Geography and Mathematics, for B, D and E. Step 3: clue 4 says B takes neither History nor Mathematics. So B takes Geography, and by clue 1 B is from Kanpur. Option (b) D and option (c) E share History and Mathematics. Option (d) fails because B is fixed.
Tip: in grid puzzles, first fill everything the clues state directly. Then use the "neither… nor" clue on the few gaps left. It usually settles one person at once.
Answer as per the official UPSC answer key.
It is possible to produce algae based biofuels, but what is/are the likely limitation(s) of developing countries in promoting this industry ?
- 1. Production of algae based biofuels is possible in seas only and not on continents.
- 2. Setting up and engineering the algae based biofuel production requires high level of expertise/technology until the construction is completed.
- 3. Economically viable production necessitates the setting up of large scale facilities which may raise ecological and social concerns.
Select the correct answer using the code given below :
Answer (b) & explanation
Statements 2 and 3 are correct (b). Statement 1 is wrong because algae can be grown on land in open ponds, in closed photobioreactors, and even in wastewater, not only at sea. The real hurdles for developing countries are that setting up and engineering these plants needs high expertise and technology (2), and that making the fuel pay needs large facilities, which use land, water and nutrients and may raise ecological and social concerns (3).
Algae are third-generation biofuels: they grow fast, make oil, and do not compete with food crops the way first-generation sugarcane and maize ethanol do. Notice India's biofuel path: the National Policy on Biofuels (2018, amended 2022) and the E20 petrol target, which India reached in 2025.
Answer as per the official UPSC answer key.
The Global Infrastructure Facility is a/an
Answer (b) & explanation
The Global Infrastructure Facility is a World Bank collaboration for infrastructure PPPs (b). It was launched in 2014, endorsed by the G20, and is hosted by the World Bank. It helps governments prepare and structure complex public-private partnerships so that private and institutional investors, such as pension funds and insurers, will put money into them. It is not an ASEAN or ADB initiative (a), it is not a group of banks working with the OECD (c), and UNCTAD does not fund it (d).
The basic problem it tackles is that there is plenty of money, but there are few "bankable" projects. Notice the Indian versions: the India Infrastructure Project Development Fund, the Viability Gap Funding scheme, and the NIIF.
Answer as per the official UPSC answer key.
What is the aim of the programme ‘Unnat Bharat Abhiyan’ ?
Answer (b) & explanation
Unnat Bharat Abhiyan connects higher education institutions with local communities (b). Launched in 2014 and coordinated by IIT Delhi, it asks higher education institutions to adopt nearby villages (at least five each). Students and teachers then use suitable technologies to solve local problems in water, energy, farming, sanitation and livelihoods. It is not a literacy mission (a), a science research upgrade (c), or a skill and welfare fund (d).
Unnat Bharat Abhiyan 2.0 (2018) opened it to all higher education institutions, and thousands have joined. Notice how it links with NEP 2020's call for community engagement and with the Sansad Adarsh Gram Yojana, where MPs adopt villages.
Answer as per the official UPSC answer key.
There are three pillars X, Y and Z of different heights. Three spiders A, B and C start to climb on these pillars simultaneously. In one chance, A climbs on X by 6 cm but slips down 1 cm. B climbs on Y by 7 cm but slips down 3 cm. C climbs on Z by 6·5 cm but slips down 2 cm. If each of them requires 40 chances to reach the top of the pillars, what is the height of the shortest pillar?
Answer (b) & explanation
The shortest pillar is 163 cm (b). Step 1: in the last chance, each spider reaches the top and does not slip. So height = 39 × (net gain per chance) + one full climb. Step 2: A on X gains 6 − 1 = 5 per chance: 39 × 5 + 6 = 201 cm. B on Y gains 7 − 3 = 4: 39 × 4 + 7 = 163 cm. C on Z gains 6.5 − 2 = 4.5: 39 × 4.5 + 6.5 = 182 cm. Step 3: the shortest is 163 cm. Option (c), 182, is Z. Option (a), 161, and option (d), 210, are errors from counting slips in the 40th chance.
Tip: in climb-and-slip puzzles, the final climb has no slip. Count it separately.
40 × 4 = 160 forgets the last climb, which has no slip.
Answer as per the official UPSC answer key.
Read the passage
Many farmers use synthetic pesticides to kill infesting insects. The consumption of pesticides in some of the developed countries is touching 3000 grams/hectare. Unfortunately, there are reports that these compounds possess inherent toxicities that endanger the health of the farm operators, consumers and the environment. Synthetic pesticides are generally persistent in environment. Entering in food chain they destroy the microbial diversity and cause ecological imbalance. Their indiscriminate use has resulted in development of resistance among insects to insecticides, upsetting of balance in nature and resurgence of treated populations. Natural pest control using the botanical pesticides is safer to the user and the environment because they break down into harmless compounds within hours or days in the presence of sunlight. Plants with pesticidal properties have been in nature for millions of years without any ill or adverse effects on the ecosystem. They are easily decomposed by many microbes common in most soils. They help in the maintenance of biological diversity of predators and the reduction of environmental contamination and human health hazards. Botanical pesticides formulated from plants are biodegradable and their use in crop protection is a practical sustainable alternative.
Which of the following statements is/are correct regarding biopesticides?
- 1. They are not hazardous to human health.
- 2. They are persistent in environment.
- 3. They are essential to maintain the biodiversity of any ecosystem.
Select the correct answer using the code given below.
Answer (a) & explanation
Only statement 1 is correct (a). Step 1: the passage says biopesticides reduce "human health hazards" and are "safer to the user". So statement 1 holds. Step 2: statement 2 says they are persistent in the environment. But the passage says they break down within hours or days. That is the opposite of persistent. Step 3: statement 3 calls them essential to biodiversity. The passage says they help biodiversity, not that it cannot exist without them. So options (b), (c) and (d) fail.
Tip: "persistent" means a chemical stays in the environment for a long time, like DDT. Biopesticides are valued because they are not persistent.
Answer as per the official UPSC answer key.
What is the total number of digits printed, if a book containing 150 pages is to be numbered from 1 to 150?
Answer (b) & explanation
The total number of digits is 342 (b). Step 1: pages 1 to 9 use 1 digit each: 9 digits. Step 2: pages 10 to 99 are 90 pages with 2 digits each: 180 digits. Step 3: pages 100 to 150 are 51 pages with 3 digits each: 153 digits. Total = 9 + 180 + 153 = 342. Option (a), 262, and option (c), 360, are calculation slips. Option (d), 450, assumes 3 digits on every page.
Tip: split page numbers into 1-digit, 2-digit and 3-digit groups. Count pages in each group carefully: from 100 to 150 there are 51 pages, not 50.
Answer as per the official UPSC answer key.
What is/are the advantage/advantages of implementing the 'National Agriculture Market' scheme ?
- 1. It is a pan-India electronic trading portal for agricultural commodities.
- 2. It provides the farmers access to nationwide market, with prices commensurate with the quality of their produce.
Select the correct answer using the code given below :
Answer (c) & explanation
Both statements are correct (c). e-NAM, launched in April 2016, is a pan-India online trading portal (1) that connects existing APMC mandis. Produce is assayed for quality, and farmers can get bids from traders across the country. This brings prices that match quality and wider demand (2), with online payment. The Small Farmers' Agribusiness Consortium (SFAC) runs it for the Agriculture Ministry. About 1,500 mandis across more than 20 States and UTs are now on it.
It also allows inter-mandi and inter-state trade, and FPOs can trade directly. Notice the hurdles: weak assaying labs, low inter-state trade, and States' APMC laws. The Model APLM Act, 2017 tried to fix these.
Answer as per the official UPSC answer key.
If you want to see gharials in their natural habitat, which one of the following is the best place to visit ?
Answer (b) & explanation
The Chambal River is the best place to see gharials (b). The National Chambal Sanctuary, set up in 1979 and shared by Madhya Pradesh, Rajasthan and Uttar Pradesh, holds most of the world's wild gharials. The gharial is Critically Endangered, needs clean, fast, sandy rivers, and eats only fish. Bhitarkanika (a) in Odisha is famous for saltwater crocodiles, not gharials. Pulicat (c) is a lagoon known for flamingos. Deepor Beel (d), near Guwahati, is a Ramsar wetland.
Smaller gharial groups live in the Girwa (Katarniaghat), Son and Gandak rivers, and in Corbett. Notice India's three crocodilians: the gharial, the mugger (marsh crocodile) and the saltwater crocodile, all on Schedule I.
Bhitarkanika does have crocodiles, but they are saltwater crocodiles.
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Answer as per the official UPSC answer key.
Which of the following are not necessarily the consequences of the proclamation of the President's rule in a State?
- 1. Dissolution of the State Legislative Assembly
- 2. Removal of the Council of Ministers in the State
- 3. Dissolution of the local bodies
Select the correct answer using the code given below :
Answer (b) & explanation
Statements 1 and 3 are not necessary results (b). Under Article 356, the President takes over the functions of the State government, so the Council of Ministers is removed (2). That always happens. The State Assembly may be dissolved or kept in suspended animation (1), so dissolution is not automatic. In S. R. Bommai (1994), the Supreme Court said the Assembly should not be dissolved until Parliament approves the proclamation. Local bodies are not affected at all (3), because they have their own constitutional status under the 73rd and 74th Amendments.
Parliament must approve President's rule within two months. It can then last six months at a time, up to three years. Notice that Bommai also made the proclamation open to judicial review.
read "not necessarily" slowly. Mark what must happen, then pick the rest.
Answer as per the official UPSC answer key.
Read the passage
There is more than a modicum of truth in the assertion that “a working knowledge of ancient history is necessary to the intelligent interpretation of current events”. But the sage who uttered these words of wisdom might well have added something on the benefits of studying particularly the famous battles of history for the lessons they contain for those of us who lead or aspire to leadership. Such a study will reveal certain qualities and attributes which enabled the winners to win—and certain deficiencies which caused the losers to lose. And the student will see that the same pattern recurs consistently, again and again, throughout the centuries.
With reference to the above passage, the following assumptions have been made :
- 1. A study of the famous battles of history would help us understand the modern warfare.
- 2. Studying the history is essential for anyone who aspires to be a leader.
Which of these assumptions is/are valid?
Answer (d) & explanation
Neither assumption is valid (d). Step 1: the passage says studying famous battles teaches qualities of leadership, such as courage and judgement. It does not say they explain modern warfare. So assumption 1 fails. Step 2: the passage calls studying history beneficial for leaders. Assumption 2 says it is essential for anyone who wants to lead. "Essential" is much stronger than "beneficial". Step 3: so assumption 2 fails too, and options (a), (b) and (c) fail.
Tip: watch the gap between "helpful" and "essential", or "useful" and "necessary". CSAT setters often swap a mild word for a strong one to make a statement false.
Answer as per the official UPSC answer key.
Consider the following :
A, B, C, D, E, F, G and H are standing in a row facing North.
B is not neighbour of G.
F is to the immediate right of G and neighbour of E.
G is not at the extreme end.
A is sixth to the left of E.
H is sixth to the right of C.
Which one of the following is correct in respect of the above?
Answer (c) & explanation
G is to the immediate right of D (c). Step 1: A is sixth to the left of E, and H is sixth to the right of C. In a row of 8, these pairs must take places 1–7 or 2–8. So A and C take places 1 and 2, and E and H take 7 and 8. Step 2: G, F, E sit together in that order. E must be 7, so F = 6 and G = 5. Then H = 8, A = 1 and C = 2. Step 3: B is not next to G, so B = 3 and D = 4. The row is A C B D G F E H. G is right of D. Options (a), (b) and (d) do not match this row.
Tip: place the "sixth to the left" pairs first; they leave few options.
Answer as per the official UPSC answer key.
With reference to Manipuri Sankirtana, consider the following statements :
- 1. It is a song and dance performance.
- 2. Cymbals are the only musical instruments used in the performance.
- 3. It is performed to narrate the life and deeds of Lord Krishna.
Which of the statements given above is/are correct ?
Answer (b) & explanation
Statements 1 and 3 are correct (b). Sankirtana of the Manipur valley is a ritual song and dance form (1) that tells the life and deeds of Krishna (3). It is performed in temples and at life events such as births and weddings, and it comes from the Vaishnav devotional tradition. Statement 2 is wrong because the performers use the pung (a barrel drum) as well as cymbals (kartal), and the drummers dance while playing.
UNESCO listed it as Intangible Cultural Heritage in 2013. Notice the related form Manipuri classical dance, with its gentle Ras Lila. Other Indian entries on the UNESCO list include Ramlila, Chhau, Kalbelia, Garba (2023) and Durga Puja in Kolkata (2021).
Answer as per the official UPSC answer key.