UPSC Prelims PYQs with explanations
Real questions from official papers, mapped to syllabus topics. Attempt each one; the answer and the reason appear instantly.
A frog tries to come out of a dried well 4·5 m deep with slippery walls. Every time the frog jumps 30 cm, slides down 15 cm. What is the number of jumps required for the frog to come out of the well?
Answer (b) & explanation
The frog needs 29 jumps (b). Step 1: each jump gives a net gain of 30 − 15 = 15 cm. But on the last jump, the frog gets out and does not slide back. Step 2: so before its final jump, the frog must reach 450 − 30 = 420 cm. That takes 420 ÷ 15 = 28 jumps. Step 3: one more jump of 30 cm takes it out: 28 + 1 = 29. Option (c), 30, uses 450 ÷ 15 without the last-jump rule. Options (a) and (d) fail.
Tip: in climbing puzzles, subtract the final full jump from the height first. Then divide the rest by the net gain, and add 1.
450/15 = 30 ignores the last jump, after which it does not slide back.
One trap spotted is one mark saved. The PYQ Book lines up every trap UPSC has set, so you walk in prepared. Try the free sample
Answer as per the official UPSC answer key.
With reference to the scholars/litterateurs of ancient India, consider the following statements :
- 1. Panini is associated with Pushyamitra Shunga.
- 2. Amarasimha is associated with Harshavardhana.
- 3. Kalidasa is associated with Chandra Gupta — II.
Which of the statements given above is/are correct ?
Answer (c) & explanation
Only statement 3 is correct (c). Statement 1 is wrong because Panini, who wrote the Sanskrit grammar Ashtadhyayi, lived around the 5th–4th century BCE, well before the Shungas (from about 185 BCE). It was Patanjali, author of the Mahabhashya on Panini's grammar, who lived under Pushyamitra Shunga. Statement 2 is wrong because Amarasimha, who wrote the Sanskrit dictionary Amarakosha, is placed among the "nine gems" of Chandragupta II, not Harsha. Statement 3 is right because Kalidasa is also placed among those nine gems.
Notice Harsha's own circle: Banabhatta, who wrote Harshacharita and Kadambari. Harsha himself wrote three plays: Nagananda, Ratnavali and Priyadarsika.
Statement 1 swaps the grammarians: Patanjali, not Panini, goes with Pushyamitra.
Answer as per the official UPSC answer key.
Consider the following pairs :
| River | Flows into
| 1. Mekong | Andaman Sea
| 2. Thames | Irish Sea
| 3. Volga | Caspian Sea
| 4. Zambezi | Indian Ocean
Which of the pairs given above is/are correctly matched ?
Answer (c) & explanation
Only pairs 3 and 4 are correct (c). Pair 1 is wrong because the Mekong, which rises in Tibet, reaches the South China Sea through its delta in Vietnam, not the Andaman Sea. Pair 2 is wrong because the Thames flows east past London into the North Sea, not the Irish Sea. Pair 3 is right because the Volga, Europe's longest river, ends in the Caspian Sea. Pair 4 is right because the Zambezi crosses Mozambique to the Indian Ocean, passing Victoria Falls on the way.
Notice the rivers that do reach the Andaman Sea: the Irrawaddy and Salween of Myanmar. The Caspian is the world's largest inland water body, with no outlet to the ocean.
Answer as per the official UPSC answer key.
Among the following Tiger Reserves, which one has the largest area under “Critical Tiger Habitat” ?
Answer (c) & explanation
Nagarjunsagar-Srisailam has the largest critical tiger habitat (c). Nagarjunsagar-Srisailam Tiger Reserve, in the Nallamala hills of Andhra Pradesh (with the adjoining Amrabad in Telangana), is India's largest tiger reserve. Its core or critical tiger habitat is about 2,600 sq km, larger than Corbett (a, about 820 sq km), Ranthambore (b, about 1,100 sq km) and Sunderbans (d, about 1,700 sq km). Critical tiger habitats are the core zones kept free of human use under Section 38V of the Wild Life (Protection) Act.
Notice Project Tiger (1973) and the NTCA (2006). India now has 58 tiger reserves (Madhav, 2025, the latest) and about 3,682 tigers (2022), around 75% of the world's wild tigers.
Answer as per the official UPSC answer key.
Read the passage
In India, agriculture still engages about half of its workforce, and about 85 per cent of its farms are small and marginal. Compared to China and Vietnam, which have experienced fast structural and rural transformation, India’s story is of slow transformation. As a result, poverty reduction in India was at a much slower pace during 1988–2014, compared to China and Vietnam. India’s poverty reduction was slow during 1988–2005, but during 2005–2012, it accelerated dramatically—almost three times faster than during the earlier period. What did India do during this period? Research reveals that the relative price scenario changed significantly (by more than 50%) in favour of agriculture in the wake of rising global prices. This boosted private investments in agriculture by more than 50%. As a result, agri-GDP growth touched 4·1% during 2007–2012 as against 2·4% during 2002–2007. The net surplus of agri-trade touched $25 billion in 2013–2014; real farm wages rose by 7% per annum. All this led to unprecedented fall in poverty.
Which one of the following statements best reflects the critical message of the passage?
Answer (d) & explanation
The critical message is that inclusive agricultural growth is key to reducing poverty soon (d). Step 1: the passage says faster farm growth, higher wages and a farm trade surplus "led to unprecedented fall in poverty". So farm growth that reaches many people cuts poverty. That is (d). Step 2: option (a), large-scale off-farm jobs, and option (b), farmer producer companies, are not discussed. Step 3: option (c), putting private over public investment, is not the passage's point.
Tip: the critical message ties together the passage's evidence. Here every fact points to farm growth reducing poverty. Pick the option that names that link, not a side topic.
Answer as per the official UPSC answer key.
In a class, there are three groups A, B and C. If one student from group A and two students from group B are shifted to group C, then what happens to the average weight of the students of the class?
Answer (c) & explanation
The class average stays the same (c). Step 1: moving students from groups A and B into group C changes the groups, but not the class. Step 2: the total weight of the class is unchanged, and so is the number of students. Step 3: average = total ÷ number, so the class average stays the same. The group averages may change, but the question asks about the whole class. Options (a), (b) and (d) fail.
Tip: read what the question asks. Shifting people inside a group never changes the overall average. Only adding or removing people from outside can change it.
the groups' averages may change, but the question asks about the class.
Answer as per the official UPSC answer key.
Which part of the Constitution of India declares the ideal of Welfare State?
Answer (a) & explanation
The Directive Principles declare the welfare state ideal (a). Part IV, the Directive Principles of State Policy, sets out the State's social and economic goals. Article 38 asks the State to promote the welfare of the people by securing a social order based on social, economic and political justice, and to reduce inequalities in income and status. Other articles cover livelihood, equal pay, health, education and help in old age. The Fundamental Rights (b) mainly limit the State. The Preamble (c) states broad ideals but does not set out the welfare state in detail. The Seventh Schedule (d) divides subjects.
Notice how welfare laws, such as MGNREGA, the Right to Education and the National Food Security Act, give legal force to DPSPs.
the Preamble speaks of justice, but the phrase "welfare of the people" lives in Article 38.
Answer as per the official UPSC answer key.
Which of the following statements are correct regarding the general difference between plant and animal cells?
- 1. Plant cells have cellulose cell walls whilst animal cells do not.
- 2. Plant cells do not have plasma membrane unlike animal cells which do.
- 3. Mature plant cell has one large vacuole whilst animal cell has many small vacuoles.
Select the correct answer using the code given below :
Answer (c) & explanation
Statements 1 and 3 are correct (c). Statement 1 is right because plant cells have a rigid cell wall made of cellulose, outside the cell membrane, which gives them shape and support. Animal cells have no cell wall. Statement 3 is right because a mature plant cell usually has one large central vacuole, filled with cell sap, which keeps the cell firm (turgid). Animal cells have only small, temporary vacuoles, or none. Statement 2 is wrong because both plant and animal cells have a plasma membrane. In plants it lies just inside the cell wall and controls what enters and leaves.
Other differences: plant cells have chloroplasts for photosynthesis, while animal cells have centrioles. Notice that fungi have walls of chitin, not cellulose.
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. Coal ash contains arsenic, lead and mercury.
- 2. Coal-fired power plants release sulphur dioxide and oxides of nitrogen into the environment.
- 3. High ash content is observed in Indian coal.
Which of the statements given above is/are correct ?
Answer (d) & explanation
All three statements are correct (d). Statement 1 is right: coal fly ash carries toxic metals such as arsenic, lead and mercury, which can leak into water and soil from ash ponds. Statement 2 is right: burning coal releases sulphur dioxide (SO₂) and oxides of nitrogen (NOₓ), which cause acid rain and smog, along with particulate matter. Statement 3 is right: most Indian coal is low grade, with 30–45% ash, far more than imported coal, so plants produce huge amounts of ash.
Notice the response: Flue Gas Desulphurisation (FGD) units to cut SO₂, and rules for 100% fly ash use in bricks, cement and roads. Indian coal is low in sulphur, which is one benefit.
Answer as per the official UPSC answer key.
Read the passage
Although most of the Genetically Modified (GM) crops cultivated now are genetically engineered for a single trait, in future, crops genetically engineered for more than one trait will be the norm. Thus, biotechnology’s role in agriculture and the regulation of the same cannot be understood solely in the context of the current generation of GM crops. Instead, there is a need to take a comprehensive look, taking into account various aspects, including socio-economic impacts, so that the potential of the technology can be harnessed while minimizing negative impacts. Given the importance of biotechnology in developing varieties that can help in climate change mitigation and adaptation, not using biotechnology as a part of the climate change action plan cannot be an option. Domestic regulation of biotechnology cannot be viewed in isolation of trade policy and obligations under various international treaties and conventions.
Which one of the following statements best implies the crux of the passage?
Answer (c) & explanation
The crux is that biotechnology's role is not limited to current GM crop priorities (c). Step 1: the passage says its role "cannot be understood solely in the context of the current generation of GM crops". That is (c), almost word for word. Step 2: option (a) is about the precautionary principle, and option (b) about biotech's present use in climate work. Neither is discussed. Step 3: option (d), that negative impacts are not understood, is not the main point.
Tip: the crux is the central claim, often stated directly. When an option repeats a key sentence in plain words, it is usually right. Options that bring in new topics are traps.
Answer as per the official UPSC answer key.
Let x, y be the volumes; m, n be the masses of two metallic cubes P and Q respectively. Each side of Q is two times that of P and mass of Q is two times that of P. Let u = m/x and v = n/y. Which one of the following is correct?
Answer (a) & explanation
u = 4v (a). Step 1: Q's sides are twice P's. Volume grows by the cube: 2 × 2 × 2 = 8. So y = 8x. Step 2: Q's mass is only twice P's: n = 2m. Step 3: v = n ÷ y = 2m ÷ 8x = ¼ × (m ÷ x) = ¼u. So u = 4v. P is four times as dense as Q. Option (b), u = 2v, wrongly doubles the volume instead of multiplying by 8. Options (c) and (d) fail.
Tip: doubling the side multiplies area by 4 and volume by 8. Here u and v are densities (mass ÷ volume). Remember the square and cube rules for scaling.
Doubling the side does not double the volume; it makes it 8 times.
Answer as per the official UPSC answer key.
As a result of 25% hike in the price of rice per kg, a person is able to purchase 6 kg less rice for ₹ 1,200. What was the original price of rice per kg?
Answer (b) & explanation
The original price was ₹ 40 per kg (b). Step 1: a 25% price rise means the same money buys 4/5 as much. So quantity falls by 1/5. Step 2: that 1/5 equals 6 kg. So the old quantity = 6 × 5 = 30 kg. Step 3: old price = 1200 ÷ 30 = ₹ 40. Check: new price = ₹ 50; 1200 ÷ 50 = 24 kg, which is 6 kg less. Options (a), (c) and (d) fail this check.
Tip: price up by 1/4 means quantity down by 1/5 (for fixed spending). Price up by 1/n means quantity down by 1/(n + 1).
Answer as per the official UPSC answer key.
With reference to the book “Desher Katha” written by Sakharam Ganesh Deuskar during the freedom struggle, consider the following statements :
- 1. It warned against the Colonial State’s hypnotic conquest of the mind.
- 2. It inspired the performance of swadeshi street plays and folk songs.
- 3. The use of ‘desh’ by Deuskar was in the specific context of the region of Bengal.
Which of the statements given above are correct ?
Answer (a) & explanation
Statements 1 and 2 are correct (a). Sakharam Ganesh Deuskar, a Marathi scholar living in Bengal, wrote the Bengali book Desher Katha (1904). It set out the British economic drain of India, drawing on Naoroji and others. Statement 1 is right because it warned against the colonial state's "hypnotic conquest" of Indian minds, which made people accept British rule as natural. Statement 2 is right because it sold thousands of copies, inspired swadeshi street plays (jatras) and folk songs, and was banned in 1910. Statement 3 is wrong because Deuskar's "desh" meant India as a whole, not Bengal alone.
Deuskar was among the first to use the word "swaraj" in Bengal. Notice the other swadeshi writers: Rabindranath Tagore, Mukunda Das (jatra) and Aurobindo.
Answer as per the official UPSC answer key.
With reference to the Indian economy after the 1991 economic liberalization, consider the following statements :
- 1. Worker productivity (₹ per worker at 2004-05 prices) increased in urban areas while it decreased in rural areas.
- 2. The percentage share of rural areas in the workforce steadily increased.
- 3. In rural areas, the growth in non-farm economy increased.
- 4. The growth rate in rural employment decreased.
Which of the statements given above is/are correct ?
Answer (b) & explanation
Statements 3 and 4 are correct (b). The answer draws on the NITI Aayog paper on India's changing rural economy (2017). Statement 1 is wrong because worker productivity rose in both rural and urban areas after 1991, though faster in towns. Statement 2 is wrong because the rural share of the workforce fell, as people moved to cities and towns. Statement 3 is right because within villages the non-farm economy (construction, trade, transport, services) grew fast and now makes up most of rural output. Statement 4 is right because rural employment growth slowed.
Notice the term "jobless growth", used for India's high GDP growth with weak job creation. The PLFS (Periodic Labour Force Survey) is now the main source on jobs.
Answer as per the official UPSC answer key.
In the context of India, which of the following is/are considered to be practice(s) of eco-friendly agriculture?
- 1. Crop diversification
- 2. Legume intensification
- 3. Tensiometer use
- 4. Vertical farming
Select the correct answer using the code given below :
Answer (a) & explanation
Items 1, 2 and 3 are eco-friendly practices (a). Item 1 is right: crop diversification breaks pest cycles, improves soil and spreads risk. Item 2 is right: legumes fix atmospheric nitrogen, cutting the need for chemical fertiliser. Item 3 is right: a tensiometer measures soil moisture, so farmers water only when needed and save water. Item 4 was not counted: in India, vertical farming is a high-energy, indoor urban technique using artificial light and controlled climate, so UPSC did not treat it as eco-friendly farm practice.
Notice other sustainable practices: zero tillage, mulching, integrated pest management, drip irrigation and natural farming. The National Mission on Natural Farming was launched in 2024.
Answer as per the official UPSC answer key.
Two Statements S1 and S2 are given below followed by a Question :
S1 : There are not more than two figures on any page of a 51-page book.
S2 : There is at least one figure on every page.
Question : Are there more than 100 figures in that book?
Which one of the following is correct in respect of the above Statements and the Question?
Answer (c) & explanation
S1 and S2 together are not sufficient (c). Step 1: S1 says at most 2 figures per page. S2 says at least 1 figure per page. Step 2: with 51 pages, the total lies between 51 × 1 = 51 and 51 × 2 = 102. Step 3: 102 is above 100, but 51 is not. So the answer could be "yes" or "no". Even together, the statements do not settle it. Options (a), (b) and (d) fail.
Tip: in data sufficiency, find the full possible range. If the range crosses the question's line (here 100), the data are not enough. S1 alone gives 0 to 102; S2 alone gives 51 or more; neither settles it.
Answer as per the official UPSC answer key.
What is the missing term @ in the following?
ACPQ : BESU :: MNGI : @
Answer (d) & explanation
The missing term is NPJM (d). Step 1: find the rule from ACPQ to BESU. A → B (+1), C → E (+2), P → S (+3), Q → U (+4). Step 2: apply it to MNGI. M + 1 = N, N + 2 = P, G + 3 = J, I + 4 = M. Step 3: so the answer is NPJM. Option (a), NPJL, ends with +3 instead of +4. Option (b), NOJM, uses +1 for the second letter. Option (c), NPIL, gets the last two wrong.
Tip: in letter analogies, write the shift for each position. A growing pattern (+1, +2, +3, +4) is very common.
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. Aadhaar metadata cannot be stored for more than three months.
- 2. State cannot enter into any contract with private corporations for sharing of Aadhaar data.
- 3. Aadhaar is mandatory for obtaining insurance products.
- 4. Aadhaar is mandatory for getting benefits funded out of the Consolidated Fund of India.
Which of the statements given above is/are correct?
Answer (b) & explanation
Statements 2 and 4 are correct (b). In Justice K.S. Puttaswamy v. Union of India (2018), the five-judge Aadhaar verdict, the Supreme Court upheld Aadhaar but limited it. Statement 1 is wrong because the Court allowed authentication records to be kept for six months, not three, cutting the earlier five years. Statement 2 is right because it struck down Section 57, which had let private companies use Aadhaar data. Statement 3 is wrong because Aadhaar cannot be made mandatory for insurance, bank accounts, mobile connections or school admissions. Statement 4 is right because Section 7 of the Aadhaar Act allows it to be required for subsidies and benefits paid from the Consolidated Fund.
Notice the 2019 amendment allowing voluntary private use, and the passing of the Aadhaar Act as a Money Bill, still being questioned.
"three months" is close to the real six. Close numbers are UPSC's favourite way to make a statement false.
Answer as per the official UPSC answer key.
In the context of recent advances in human reproductive technology, “Pronuclear Transfer” is used for
Answer (d) & explanation
Pronuclear transfer prevents mitochondrial diseases (d). Mitochondria have their own small set of DNA, passed on only from the mother. Faults in it cause serious diseases of the muscles, brain and heart. In pronuclear transfer, the egg of the mother is fertilised by the father's sperm. The two pronuclei, holding the parents' main DNA, are moved into a donor egg that has healthy mitochondria and whose own nuclei have been removed. The child gets the parents' genes but healthy mitochondria, hence the term "three-parent babies". It is not normal IVF (a), editing of sperm-making cells (b), or turning stem cells into embryos (c).
The UK legalised the method in 2015. Notice that in 2025, UK doctors reported eight babies born using it.
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. In the case of all cereals, pulses and oil-seeds, the procurement at Minimum Support Price (MSP) is unlimited in any State/UT of India.
- 2. In the case of cereals and pulses, the MSP is fixed in any State/UT at a level to which the market price will never rise.
Which of the statements given above is/are correct ?
Answer (d) & explanation
Neither statement is correct (d). Statement 1 is wrong because MSP is announced for 22 crops, but open-ended procurement happens mainly for wheat and rice, and only in some States. Pulses and oilseeds are bought under PM-AASHA (Price Support Scheme), usually only up to about 25% of output in a State. Statement 2 is wrong because MSP is a floor, not a ceiling. Market prices often rise above MSP, as with pulses and many oilseeds in recent years.
Notice that the Commission for Agricultural Costs and Prices (CACP) recommends MSP and the Cabinet Committee on Economic Affairs approves it. Since 2018–19, MSP has been set at least 1.5 times the A2+FL cost of production. MSP has no legal backing.
"unlimited" and "never". Two absolute words make both statements fail.
Answer as per the official UPSC answer key.