UPSC Prelims PYQs with explanations
Real questions from official papers, mapped to syllabus topics. Attempt each one; the answer and the reason appear instantly.
Consider the following statements followed by two conclusions :
Statements : Some men are great. Some men are wise.
Conclusion I : Men are either great or wise.
Conclusion II : Some men are neither great nor wise.
Which one of the following is correct ?
Answer (d) & explanation
Neither conclusion is valid (d). Step 1: "Some men are great" and "Some men are wise" tell us only about some men. They say nothing about the rest. Step 2: test conclusion I: "Men are either great or wise." This would mean every man is at least one of the two. The statements do not say that. So I fails. Step 3: test conclusion II: "Some men are neither great nor wise." This might be true, but it is not certain: perhaps every man is great or wise. So II fails too. Options (a), (b) and (c) fail.
Tip: "some" gives no information about the others. A valid conclusion must be certain, not just possible.
Answer as per the official UPSC answer key.
Consider the following statements regarding the Directive Principles of State Policy :
- 1. The Principles spell out the socio-economic democracy in the country.
- 2. The provisions contained in these Principles are not enforceable by any court.
Which of the statements given above is/are correct?
Answer (c) & explanation
Both statements are correct (c). Fundamental Rights give political democracy; the Directive Principles aim at social and economic democracy: livelihood, fair wages, health, education and reduced inequality (1). Article 37 makes them non-justiciable: no court can enforce them, though they are fundamental in the governance of the country (2).
B. R. Ambedkar called them "novel features" of the Constitution, and they draw on the Irish Constitution. In Minerva Mills (1980) the Court held that harmony between Fundamental Rights and DPSPs is part of the basic structure. Notice how many laws, from MGNREGA to the RTE, give life to these principles.
Answer as per the official UPSC answer key.
Which of the following kingdoms were associated with the life of the Buddha?
- 1. Avanti
- 2. Gandhara
- 3. Kosala
- 4. Magadha
Select the correct answer using the code given below.
Answer (d) & explanation
The Buddha lived and taught mostly in Kosala and Magadha, so the answer is (d). In Kosala he spent many rainy seasons at Shravasti, with King Prasenajit. In Magadha he attained enlightenment at Bodh Gaya and was patronised by Bimbisara and later Ajatashatru at Rajagriha. Avanti and Gandhara were mahajanapadas he did not visit, so options with 1 or 2 fail.
Buddhism later spread to Avanti through disciples like Mahakachchana, and Gandhara became a great centre of Buddhist art under the Kushanas. Notice how UPSC repeated this exact question from 2014.
Answer as per the official UPSC answer key.
In which of the following activities are Indian Remote Sensing (IRS) satellites used?
- 1. Assessment of crop productivity
- 2. Locating groundwater resources
- 3. Mineral exploration
- 4. Telecommunications
- 5. Traffic studies
Select the correct answer using the code given below.
Answer (a) & explanation
IRS satellites, such as Resourcesat, Cartosat and Oceansat, image the earth for crop production forecasts (1), groundwater prospect maps (2) and mineral and geological mapping (3). So the answer is (a). Telecommunication (4) is the job of the GSAT/INSAT series, and UPSC's key does not count traffic studies (5).
IRS data also supports forest mapping, urban planning, disaster monitoring and the FASAL crop forecasting programme. Bhuvan is ISRO's geoportal that shares this data. Notice how India built its space programme around development needs.
Answer as per the official UPSC answer key.
Read the passage
By 2050, the Earth’s population will likely have swelled from seven to nine billion people. To fill all those stomachs — while accounting for shifting consumption patterns, climate change, and a finite amount of arable land and potable water — some experts say food production will have to double. How can we make the numbers add up ? Experts say higher yielding crop varieties and more efficient farming methods will be crucial. So will waste reduction. Experts urge cities to reclaim nutrients and water from waste streams and preserve farmland. Poor countries, they say, can improve crop storage and packaging and rich nations could cut back on resource-intensive foods like meat.
Which one of the following statements best sums up the above passage ?
Answer (d) & explanation
Food security is increasingly a collective challenge (d). Step 1: see who has a role in the passage. Experts propose better crops and methods; cities should reclaim nutrients and water; poor countries should improve storage; rich nations should eat less meat. Everyone must act together, so it is a collective challenge. Step 2: test the others. Option (a) is only the starting fact, not the summary. Option (b) is wrong: the word "only" fails, as rich nations are also involved. Option (c) is wrong: it is defeatist, while the passage offers solutions to "make the numbers add up".
Tip: a good summary covers the whole passage. When a passage lists many actors with many roles, the summary is usually about shared responsibility.
Answer as per the official UPSC answer key.
In a 500 metres race, B starts 45 metres ahead of A, but A wins the race while B is still 35 metres behind. What is the ratio of the speeds of A to B assuming that both start at the same time?
Answer (a) & explanation
The speed ratio of A to B is 25 : 21 (a). Step 1: A runs the full 500 m. Step 2: B starts 45 m ahead, so B has only 455 m to run. When A finishes, B is still 35 m short. So B has run 455 − 35 = 420 m. Step 3: in the same time, A ran 500 m and B ran 420 m. Speed ratio = 500 : 420. Divide both by 20: 25 : 21. Options (b), (c) and (d) do not match.
Tip: when two runners run for the same time, their speeds are in the same ratio as their distances. Work out exactly how far each actually ran.
500 : 400 (= 25 : 20) forgets one of the two gaps.
Answer as per the official UPSC answer key.
Read the passage
Climate change is a complex policy issue with major implications in terms of finance. All actions to address climate change ultimately involve costs. Funding is vital for countries like India to design and implement adaptation and mitigation plans and projects. Lack of funding is a large impediment to implementing adaptation plans. The scale and magnitude of the financial support required by developing countries to enhance their domestic mitigation and adaptation actions are a matter of intense debate in the multilateral negotiations under the United Nations Framework Convention on Climate Change (UNFCCC). The Convention squarely puts the responsibility for provision of financial support on the developed countries, taking into account their contribution to the stock of greenhouse gases (GHGs) in the atmosphere. Given the magnitude of the task and the funds required, domestic finances are likely to fall short of the current and projected needs of the developing countries. Global funding through the multilateral mechanism of the Convention will enhance their domestic capacity to finance the mitigation efforts.
With regards to developing countries, it can be inferred from the passage that climate change is likely to have implications on their
- 1. domestic finances.
- 2. capacity for multilateral trade.
Select the correct answer using the code given below :
Answer (a) & explanation
Only domestic finances are affected (a). Step 1: test item 1. The passage says "domestic finances are likely to fall short of the current and projected needs of the developing countries". So climate change affects their domestic finances. 1 holds. Step 2: test item 2. The word "multilateral" appears, but only in "multilateral negotiations" and the "multilateral mechanism" for funding. Trade is never mentioned. So 2 fails. Options (b), (c) and (d) fail.
Tip: UPSC often reuses a passage word ("multilateral") in a new context ("trade") to trap careless readers. Check that the whole phrase, not just one word, is in the passage.
Answer as per the official UPSC answer key.
With reference to ‘fly ash’ produced by the power plants using coal as fuel, which of the following statements is/are correct?
- 1. Fly ash can be used in the production of bricks for building construction.
- 2. Fly ash can be used as a replacement for some of the Portland cement contents of concrete.
- 3. Fly ash is made up of silicon dioxide and calcium oxide only, and does not contain any toxic elements.
Select the correct answer using the code given below.
Answer (a) & explanation
Statements 1 and 2 are correct (a). Fly ash is used to make bricks and blocks (1), and it replaces part of the cement in Portland Pozzolana Cement and concrete (2). Statement 3 is wrong: besides silica, alumina, iron oxide and lime, fly ash carries traces of arsenic, lead, mercury and other toxic metals.
That is why ash ponds and their breaches pollute the land and water around power plants. Rules under the Environment (Protection) Act require thermal plants to achieve 100% utilisation of fly ash. Notice how a waste becomes a resource: the idea of a circular economy.
Answer as per the official UPSC answer key.
Indira Gandhi Prize for Peace, Disarmament and Development for 2014 was given to which one of the following?
Answer (c) & explanation
The Indira Gandhi Prize for Peace, Disarmament and Development for 2014 went to ISRO (c), for using space technology for development and for achievements such as the Mars Orbiter Mission. BARC (a), IISc (b) and TIFR (d) are leading science institutions but did not receive the 2014 award.
The prize is given by the Indira Gandhi Memorial Trust. Earlier winners include Mikhail Gorbachev, Médecins Sans Frontières and the UNHCR. Notice how India's space programme is framed around development: weather, communication and resource mapping, not just exploration. Mangalyaan made India the first to reach Mars orbit on its first try.
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. The Legislative Council of a State in India can be larger in size than half of the Legislative Assembly of that particular State.
- 2. The Governor of a State nominates the Chairman of Legislative Council of that particular State.
Which of the statements given above is/are correct?
Answer (d) & explanation
Neither statement is correct (d). Article 171(1) caps a Legislative Council at one-third of the Assembly's strength, with a minimum of 40, so it cannot exceed half. The Council elects its own Chairman from among its members under Article 182; the Governor does not nominate him.
The Governor nominates about one-sixth of the members, from fields such as literature, science, art, cooperation and social service. Only a few States have Councils, among them Uttar Pradesh, Bihar, Maharashtra, Karnataka, Andhra Pradesh and Telangana. Under Article 169, Parliament can create or abolish one on the Assembly's resolution.
"half" for one-third, "nominates" for elects. Two wrong words in two lines.
Answer as per the official UPSC answer key.
What is the missing number 'X' of the series 7, X, 21, 31, 43 ?
Answer (c) & explanation
X is 13 (c). Step 1: look at the gaps between the known numbers: 21 to 31 is 10, and 31 to 43 is 12. The gaps grow by 2 each time. Step 2: work backwards. The gap before 10 is 8, and the one before that is 6. Step 3: X = 7 + 6 = 13. Check: 13 + 8 = 21. Correct. Options (a), (b) and (d) break the pattern.
Tip: in number series, first write the differences between neighbours. If the differences themselves form a simple pattern (here +2 each time), the series is easy to complete in both directions.
Answer as per the official UPSC answer key.
Read the passage
The existence/establishment of formal financial institutions that offer safe, reliable, and alternative financial instruments is fundamental in mobilising savings. To save, individuals need access to safe and reliable financial institutions, such as banks, and to appropriate financial instruments and reasonable financial incentives. Such access is not always available to all people in developing countries like India and more so, in rural areas. Savings help poor households manage volatility in cash flow, smoothen consumption, and build working capital. Poor households without access to a formal savings mechanism encourage immediate spending temptations.
With reference to the above passage, consider the following statements :
- 1. Indian financial institutions do not offer any financial instruments to rural households to mobilise their savings.
- 2. Poor households tend to spend their earnings/savings due to lack of access to appropriate financial instruments.
Which of the statements given above is/are correct ?
Answer (b) & explanation
Only statement 2 is correct (b). Step 1: test statement 2. The passage says poor households without access to a formal savings mechanism face "immediate spending temptations". So they spend their earnings because they lack suitable instruments. 2 holds. Step 2: test statement 1. The passage says access is "not always available to all people", especially in rural areas. That is different from saying institutions offer no instruments at all. So 1 goes too far. Options (a), (c) and (d) fail.
Tip: "not always available" means some people lack access, not everyone. UPSC often turns a partial problem into a total one to make a wrong statement.
Answer as per the official UPSC answer key.
A cow costs more than 4 goats but less than 5 goats. If a goat costs between ₹ 600 and ₹ 800, which of the following is a most valid conclusion?
Answer (d) & explanation
A cow costs between ₹2,400 and ₹4,000 (d). Step 1: the cow costs more than 4 goats and less than 5 goats. A goat costs between ₹600 and ₹800. Step 2: the lowest a cow could cost is just over 4 × 600 = ₹2,400. Step 3: the highest is just under 5 × 800 = ₹4,000. Step 4: only option (d) covers every possible price. Option (a) is too narrow at the bottom (a cow might cost ₹2,450). Option (b) misses prices up to ₹4,000. Option (c) misses both ends.
Tip: for a "most valid" range, use the smallest values together for the minimum and the largest values together for the maximum.
(a), (b) and (c) can fail. A cow could cost ₹ 2,450 or ₹ 3,900. The most valid conclusion is the one that always holds.
Answer as per the official UPSC answer key.
Which of the following brings out the 'Consumer Price Index Number for Industrial Workers'?
Answer (c) & explanation
The CPI for Industrial Workers is compiled by the Labour Bureau, Shimla, under the Ministry of Labour (c), as are the CPIs for Agricultural and Rural Labourers. It is used to fix dearness allowance for government employees and wages in industry. The RBI (a) uses inflation data but does not compile CPI-IW; the Department of Economic Affairs (b) and DoPT (d) do not compile it either.
The headline CPI (Rural, Urban, Combined) used for inflation targeting is compiled by the NSO under MoSPI. Notice how different price indices serve different purposes: wages, policy and contracts.
Answer as per the official UPSC answer key.
Who/Which of the following is the custodian of the Constitution of India?
Answer (d) & explanation
The Supreme Court is the custodian of the Constitution (d). It interprets the Constitution, enforces Fundamental Rights under Article 32 and strikes down laws that violate it through judicial review. The President (a) swears to "preserve, protect and defend" the Constitution but has no power to enforce it. The Prime Minister (b) heads the executive, and the Lok Sabha Secretariat (c) is an administrative office.
In Kesavananda Bharati (1973) the Court laid down the basic structure doctrine, limiting Parliament's power to amend. Notice how this makes the Court the final guardian of constitutional values.
the President's oath has the words "protect and defend", which pulls you to (a).
Answer as per the official UPSC answer key.
With reference to ‘fuel cells’ in which hydrogen-rich fuel and oxygen are used to generate electricity, consider the following statements :
- 1. If pure hydrogen is used as a fuel, the fuel cell emits heat and water as by-products.
- 2. Fuel cells can be used for powering buildings and not for small devices like laptop computers.
- 3. Fuel cells produce electricity in the form of Alternating Current (AC).
Which of the statements given above is/are correct?
Answer (a) & explanation
Only statement 1 is correct (a). A hydrogen fuel cell combines hydrogen and oxygen electrochemically and gives off only water and heat (1). Statement 2 is wrong: fuel cells come in all sizes, from micro cells for laptops to megawatt units for buildings. Statement 3 is wrong: their output is direct current, which an inverter converts to AC.
Fuel cells are clean at the point of use, but their green credentials depend on how the hydrogen is made. India's National Green Hydrogen Mission (2023) aims for 5 million tonnes a year by 2030. Notice how this links chemistry to clean energy policy.
Answer as per the official UPSC answer key.
Read the passage
Our municipal corporations are understaffed. The issue of skills and competencies of the staff poses an even greater challenge. Urban services delivery and infrastructure are complex to plan and execute. They require a high degree of specialization and professionalism. The current framework within which municipal employees, including senior Management, are recruited does not adequately factor in the technical and managerial competencies required. Cadre and recruitment rules only specify the bare minimum in academic qualifications. There is no mention of managerial or technical competencies, or of relevant work experience. This is the case with most municipal corporations. They also suffer from weak organisation design and structure.
Which among the following is the most logical and rational assumption that can be made from the above passage ?
Answer (b) & explanation
Cities can do better if local bodies have adequate skilled staff (b). Step 1: find the problems. Municipal bodies are "understaffed", and the bigger challenge is staff skills and competencies. Recruitment rules ignore technical and managerial abilities. So the hidden assumption is that more and better-skilled staff would improve city life. Step 2: test the others. Option (a) is wrong: expanding organisations ignores the skills problem. Option (c) is wrong: the cause given is recruitment rules, not missing training institutions. Option (d) is wrong: the demographic dividend is not mentioned.
Tip: an assumption links the problem described to the result the author wants. Here: fix staff and skills, and services improve.
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. Some claim to have seen UFOs (Unidentified Flying Objects).
- 2. Life on other heavenly bodies is considered to be a possibility.
- 3. Voyage to space is now an established fact.
From the above statements, it may be concluded that
Answer (d) & explanation
Nothing definite can be said about UFOs (d). Step 1: weigh each statement. Statement 1 is only a claim that some people have seen UFOs. Statement 2 says life elsewhere is only a possibility. Statement 3 is about human space travel, not UFOs. Step 2: none of these tells us what UFOs are or where they come from. Step 3: test the others. Option (a), saying UFOs are heavenly bodies, is not supported. Option (b), saying they come from other worlds, is a guess. Option (c), about more intelligent species, is not mentioned at all.
Tip: claims and possibilities cannot be joined into a definite conclusion. When statements are weak, the safe answer is often "nothing definite".
Answer as per the official UPSC answer key.
In the 'Index of Eight Core Industries', which one of the following is given the highest weight?
Answer (b) & explanation
The Index of Eight Core Industries, released by the Office of the Economic Adviser in DPIIT, covers coal, crude oil, natural gas, refinery products, fertilisers, steel, cement and electricity. On the 2011-12 base, refinery products weigh about 28% and electricity about 20% (b). Steel (d) is about 18%, coal (a) about 10% and fertilisers (c) under 3%. Among the options, electricity is the highest.
Together these eight industries make up about 40% of the Index of Industrial Production. Notice how core-sector data is watched as an early signal of where the wider economy is heading.
refinery products are heavier still, but they are not among the options.
Answer as per the official UPSC answer key.
Which one of the following is associated with the issue of control and phasing out of the use of ozone-depleting substances?
Answer (b) & explanation
The Montreal Protocol (1987), under the Vienna Convention (1985), phases out ozone-depleting substances such as CFCs and halons (b). It is the first UN treaty ratified by every country. Bretton Woods (a) created the IMF and World Bank in 1944. The Kyoto Protocol (c) dealt with greenhouse gases, and the Nagoya Protocol (d) with access and benefit-sharing of genetic resources.
Its Kigali Amendment (2016) adds HFCs, which do not harm ozone but are strong greenhouse gases. Notice how the ozone layer is healing, a rare success story of global cooperation.
Answer as per the official UPSC answer key.