UPSC Prelims PYQs with explanations
Real questions from official papers, mapped to syllabus topics. Attempt each one; the answer and the reason appear instantly.
(Same information as the question above.)
If the route between G and C is closed, which one of the following stations need not be passed through while travelling from H to C?
Answer (c) & explanation
Station A need not be passed (c). Step 1: with the G to C passage closed, find a way from H to C. From H, the only way out is the one-way passage H to G. Step 2: from G, the only way out now is G to B (two-way). From B: one-way B to F. From F: F to D. From D: D to E. From E: one-way E to C. Step 3: the only route is H → G → B → F → D → E → C. Station A is not on it. Options (a) E, (b) D and (d) B are all on the route.
Tip: when a passage is closed, re-draw just that part of the map. Then trace the only path left; stations off it are the answer.
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. In tropical regions, Zika virus disease is transmitted by the same mosquito that transmits dengue.
- 2. Sexual transmission of Zika virus disease is possible.
Which of the statements given above is/are correct ?
Answer (c) & explanation
Both statements are correct (c). Zika, a flavivirus, is spread mainly by Aedes aegypti (1). This is the same day-biting mosquito that carries dengue, chikungunya and yellow fever, and it breeds in clean, standing water. Zika can also spread sexually (2), through blood transfusion, and from mother to foetus, where it can cause microcephaly (an abnormally small head). The 2015–16 outbreak in Brazil led the WHO to declare a public health emergency of international concern.
India has seen outbreaks in Gujarat (2017), Rajasthan, Kerala and Maharashtra. Notice the control methods, such as source reduction and Wolbachia-infected mosquitoes that cut virus spread. Also remember the different carrier for malaria: the Anopheles mosquito.
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. Climate and Clean Air Coalition (CCAC) to Reduce Short Lived Climate Pollutants is a unique initiative of G20 group of countries.
- 2. The CCAC focuses on methane, black carbon and hydrofluorocarbons.
Which of the statements given above is/are correct ?
Answer (b) & explanation
Only statement 2 is correct (b). Statement 1 is wrong because the Climate and Clean Air Coalition (CCAC) was started in 2012 by UNEP and six countries: Bangladesh, Canada, Ghana, Mexico, Sweden and the USA. It is not a G20 body. Statement 2 is right because it targets short-lived climate pollutants: methane, black carbon, HFCs and tropospheric ozone. These stay in the air only days to years, so cutting them slows warming quickly and also cleans the air.
India joined the CCAC in 2019. Notice the related efforts: the Global Methane Pledge (COP26, 30% cut by 2030), which India has not signed, and the Kigali Amendment (2016) to phase down HFCs, which India ratified in 2021.
Answer as per the official UPSC answer key.
Out of the following statements, choose the one that brings out the principle underlying the Cabinet form of Government :
Answer (c) & explanation
The principle is collective responsibility to the people (c). In the cabinet form of government, the Council of Ministers stands or falls together. Under Article 75(3), it is collectively responsible to the Lok Sabha, and through it to the people. Ministers must defend cabinet decisions in public or resign. Reducing criticism (a), speeding up work (b), and strengthening the leader (d) are not its defining principle; at most, they are side effects.
The Prime Minister is "first among equals", though in practice the PM is much more powerful. Notice the difference between collective responsibility (to the Lok Sabha, Art. 75(3)) and individual responsibility (to the President, Art. 75(2)). Ministers hold office "during the pleasure" of the President.
Answer as per the official UPSC answer key.
Read the passage
In a free country, the man who reaches the position of leader is usually one of outstanding character and ability. Moreover, it is usually possible to foresee that he will reach such a position, since early in life one can see his qualities of character. But this is not always true in the case of a dictator; often he reaches his position of power through chance, very often through the unhappy state of his country.
The passage seems to suggest that:
Answer (d) & explanation
The passage suggests that despair in a country sometimes leads to dictatorship (d). Step 1: it says a dictator often rises "through the unhappy state of his country". So a nation's despair can open the way to a dictator. That is option (d). Step 2: option (a) says the leader foresees his own rise. But in the passage it is others who foresee it. Step 3: option (b) says leaders are chosen only by free countries, which is too extreme. Option (c), that a leader must free his country from despair, is not the point.
Tip: history fits this idea; hard times in Germany helped Hitler rise. But always answer from the passage first.
Answer as per the official UPSC answer key.
If 2 boys and 2 girls are to be arranged in a row so that the girls are not next to each other, how many possible arrangements are there?
Answer (c) & explanation
There are 12 arrangements (c). Step 1: four different children can stand in 4 × 3 × 2 × 1 = 24 orders. Step 2: count the orders with the girls together. Tie the 2 girls into one block. Now there are 3 items, which can be arranged in 3 × 2 × 1 = 6 ways. The girls can swap inside the block, so × 2 = 12. Step 3: girls apart = 24 − 12 = 12. Option (d), 24, counts all orders. Option (b), 6, and option (a), 3, undercount.
Tip: for "not next to each other", count all orders and subtract those where they are together. Treating a pair as one block makes the "together" count easy.
Answer as per the official UPSC answer key.
Which of the following statements is/are correct regarding Smart India Hackathon 2017?
- 1. It is a centrally sponsored scheme for developing every city of our country into Smart Cities in a decade.
- 2. It is an initiative to identify new digital technology innovations for solving the many problems faced by our country.
- 3. It is a programme aimed at making all the financial transactions in our country completely digital in a decade.
Select the correct answer using the code given below :
Answer (b) & explanation
Only statement 2 is correct (b). Smart India Hackathon, first held in 2017 by the Ministry of Education (then MHRD), AICTE and partners, is a nationwide contest where students build digital and hardware solutions to real problems set by ministries, states and industry (2). Statement 1 is wrong because it is not the Smart Cities Mission (2015), which develops 100 chosen cities. Statement 3 is wrong because it is not a plan to make all financial transactions digital; that was the push behind Digital India, UPI and BHIM.
It is now one of the world's largest open innovation events. Notice how it links with Atal Innovation Mission (Atal Tinkering Labs) and Startup India, as part of building an innovation culture.
Answer as per the official UPSC answer key.
Which of the following is a most likely consequence of implementing the 'Unified Payments Interface (UPI)' ?
Answer (a) & explanation
With UPI, mobile wallets are no longer needed for online payments (a). The Unified Payments Interface, launched by NPCI in 2016, moves money straight from one bank account to another using a phone and a virtual payment address or QR code. There is no need to first load money into a mobile wallet. Option (b) is exaggerated because cash is still widely used. Option (c) has no link to FDI. Option (d) is wrong because subsidies go through DBT using the Aadhaar Payment Bridge, not UPI.
UPI now handles about 20 billion transactions a month and is going global, with links to Singapore's PayNow, the UAE and France. Notice the newer features too: UPI Lite, credit cards on UPI, and UPI 123PAY for feature phones.
option (d) sounds good and is linked to digital payments. The "most likely" direct result is the end of the need for wallets.
Answer as per the official UPSC answer key.
Which of the following has/have occurred in India after its liberalization of economic policies in 1991 ?
- 1. Share of agriculture in GDP increased enormously.
- 2. Share of India's exports in world trade increased.
- 3. FDI inflows increased.
- 4. India's foreign exchange reserves increased enormously.
Select the correct answer using the codes given below :
Answer (b) & explanation
Statements 2, 3 and 4 are correct (b). After the 1991 reforms (the LPG model), FDI rose from almost nothing to tens of billions of dollars a year (3). Forex reserves climbed from about $1 billion in mid-1991, when India pledged gold, to over $300 billion by 2008 (4). They are now about $700 billion. India's share of world exports rose from about 0.5% to around 2% (2). Statement 1 is wrong because agriculture's share of GDP fell, from about 30% to under 20%, as services grew. Agriculture still employs about 45% of workers.
Notice this pattern: India's growth skipped a manufacturing phase and went from agriculture straight to services. That is why schemes like Make in India and PLI aim to raise manufacturing's share.
Answer as per the official UPSC answer key.
Read the passage
Why do people prefer open defecation and not want toilets or, if they have them, only use them sometimes? Recent research has shown two critical elements : ideas of purity and pollution, and not wanting pits or septic tanks to fill because they have to be emptied. These are the issues that nobody wants to talk about, but if we want to eradicate the practice of open defecation, they have to be confronted and dealt properly.
Which among the following is the most crucial message conveyed by the above passage?
Answer (b) & explanation
The crucial message is that people must see toilet use and pit-emptying as clean, not polluting (b). Step 1: the passage says ideas of purity and pollution, and the dislike of emptying pits, "have to be confronted". So people's view of toilets must change. That is option (b). Step 2: options (a) and (c) say these ideas cannot be removed and people cannot change. That contradicts the call to act. Step 3: option (d), that people have no civic sense or privacy, is not the passage's claim.
Tip: when the author says something "has to be" done, the author believes change is possible. So options saying "cannot" go against the author. Swachh Bharat faced exactly this behaviour challenge.
Answer as per the official UPSC answer key.
Six boys A, B, C, D, E and F play a game of cards. Each has a pack of 10 cards. F borrows 2 cards from A and gives away 5 to C who in turn gives 3 to B while B gives 6 to D who passes on 1 to E. Then the number of cards possessed by D and E is equal to the number of cards possessed by
Answer (b) & explanation
D and E together have as many cards as B, C and F (b). Step 1: everyone starts with 10. F borrows 2 from A: A 8, F 12. F gives 5 to C: F 7, C 15. Step 2: C gives 3 to B: C 12, B 13. B gives 6 to D: B 7, D 16. D gives 1 to E: D 15, E 11. Step 3: final count: A 8, B 7, C 12, D 15, E 11, F 7. D + E = 26. B + C + F = 7 + 12 + 7 = 26. Option (a) gives 27. Option (c) gives 22. Option (d) gives 27.
Tip: track each person's count after every move in a small table. Check that the total stays 60; if not, you have made a slip.
Answer as per the official UPSC answer key.
The average rainfall in a city for the first four days was recorded to be 0·40 inch. The rainfall on the last two days was in the ratio of 4 : 3. The average of six days was 0·50 inch. What was the rainfall on the fifth day?
Answer (c) & explanation
Rainfall on the fifth day was 0.80 inch (c). Step 1: total over six days = 6 × 0.50 = 3.00 inches. Total over the first four days = 4 × 0.40 = 1.60 inches. Step 2: so the last two days had 3.00 − 1.60 = 1.40 inches. Step 3: these are in the ratio 4 : 3. 1.40 ÷ 7 = 0.20, so the fifth day = 4 × 0.20 = 0.80 inch and the sixth = 0.60 inch. Option (a), 0.60, is the sixth day. Options (b) and (d) do not fit.
Tip: in average questions, turn every average into a total first. Then subtract to find the missing part, and split it by the ratio.
Answer as per the official UPSC answer key.
Due to some reasons, if there is a huge fall in the population of species of butterflies, what could be its likely consequence/consequences ?
- 1. Pollination of some plants could be adversely affected.
- 2. There could be a drastic increase in the fungal infections of some cultivated plants.
- 3. It could lead to a fall in the population of some species of wasps, spiders and birds.
Select the correct answer using the code given below :
Answer (c) & explanation
Statements 1 and 3 are correct (c). Butterflies are pollinators of many flowering plants, so a big fall in their numbers could hurt pollination (1). Butterflies and their caterpillars are also food for wasps (some lay eggs in caterpillars), spiders and birds. Losing them would affect these predators further up the food web (3). Statement 2 has no link. Butterflies do not control plant fungi, so their loss would not cause a sudden rise in fungal infections of crops.
Butterflies are also bio-indicators, sensitive to pesticides and climate change. Notice the wider idea of a trophic cascade: losing one link in the food web can ripple through the whole ecosystem, much like declines in bees threaten food security.
Answer as per the official UPSC answer key.
With reference to 'National Investment and Infrastructure Fund', which of the following statements is/are correct ?
- 1. It is an organ of NITI Aayog.
- 2. It has a corpus of ₹4,00,000 crore at present.
Select the correct answer using the code given below :
Answer (d) & explanation
Neither statement is correct (d). The National Investment and Infrastructure Fund (NIIF), set up in 2015, is a fund manager registered with SEBI as an Alternative Investment Fund. It was set up by the Ministry of Finance (Department of Economic Affairs), not NITI Aayog, so statement 1 is wrong. Its planned corpus was ₹40,000 crore, with the government putting in up to 49% and the rest coming from investors such as Abu Dhabi's ADIA, Temasek and AIIB. Statement 2 adds an extra zero.
It runs a Master Fund, a Fund of Funds and a Strategic Opportunities Fund. Notice the other infrastructure-finance bodies: NaBFID (2021) is a development finance institution, and the National Infrastructure Pipeline listed the projects.
the extra zero. Count the digits in big figures.
Answer as per the official UPSC answer key.
What is the purpose of ‘Vidyanjali Yojana’ ?
- 1. To enable the famous foreign educational institutions to open their campuses in India.
- 2. To increase the quality of education provided in government schools by taking help from the private sector and the community.
- 3. To encourage voluntary monetary contributions from private individuals and organizations so as to improve the infrastructure facilities for primary and secondary schools.
Select the correct answer using the code given below :
Answer (a) & explanation
Only statement 2 is correct (a). Vidyanjali, launched in 2016 by the Ministry of Education (then MHRD), links volunteers such as retired teachers, professionals, NRIs and community members with government schools. They help with teaching, reading and co-curricular activities, improving quality with the support of the community and private sector (2). Statement 1 is wrong because foreign campuses are governed by separate UGC regulations (2023). Statement 3 is wrong because, when the question was set, Vidyanjali was about volunteering, not money.
The later Vidyanjali 2.0 portal (2021) added donations of assets, equipment and materials. Notice how this fits NEP 2020's focus on community involvement and on school complexes.
Answer for 2017. The later portal's donation feature does not change this key.
Answer as per the official UPSC answer key.
Consider the following :
Statement : Good voice is a natural gift but one has to keep practising to improve and excel well in the field of music.
Conclusions :
- I. Natural gifts need nurturing and care.
- II. Even though one's voice is not good, one can keep practising.
Which one of the following is correct in respect of the above statement and conclusions?
Answer (a) & explanation
Only conclusion I follows (a). Step 1: the statement says a good voice is a natural gift, but one must keep practising to excel. So even a natural gift needs work and care. That is conclusion I. Step 2: conclusion II is about people without a good voice practising. The statement says nothing about such people. So II does not follow. Step 3: so option (b), only II, and option (c), either I or II, fail. Option (d), neither, fails because I follows.
Tip: a conclusion must stay within what the statement talks about. If the statement is only about people with good voices, you cannot conclude anything about people without them.
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.
On the basis of the above passage, the following assumptions have been made :
- 1. Synthetic pesticides should never be used in modern agriculture.
- 2. One of the aims of sustainable agriculture is to ensure minimal ecological imbalance.
- 3. Botanical pesticides are more effective as compared to synthetic pesticides.
Which of the assumptions given above is/are correct?
Answer (b) & explanation
Only assumption 2 is correct (b). Step 1: the passage calls botanical pesticides the "sustainable alternative" because they avoid ecological imbalance. So one aim of sustainable farming is minimal imbalance. Assumption 2 holds. Step 2: assumption 1 says synthetic pesticides should never be used. But the passage faults "indiscriminate use", not all use. Step 3: assumption 3 says botanicals are more effective. The passage compares their safety, not their power. So 1 and 3 fail, and options (a), (c) and (d) fail.
Tip: separate "safer" from "more effective". Neem-based pesticides are safer for people and nature, but the passage never says they kill pests better.
Answer as per the official UPSC answer key.
There are certain 2-digit numbers. The difference between the number and the one obtained on reversing it is always 27. How many such maximum 2-digit numbers are there?
Answer (d) & explanation
None of the options is right (d). Step 1: number − reverse = 9 × (difference of the digits). For a difference of 27, the digits must differ by 3. Step 2: numbers where the tens digit is 3 more than the units digit: 41, 52, 63, 74, 85 and 96. That is 6. Their reverses (14, 25, 36, 47, 58, 69) also differ by 27, if we allow the difference either way, giving 12. Step 3: 30 has reverse 03, which is not a 2-digit number. So the count is 6 or 12, never 3, 4 or 5. Options (a), (b) and (c) fail.
Tip: learn that any 2-digit number minus its reverse is a multiple of 9.
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. The Standard Mark of Bureau of Indian Standards (BIS) is mandatory for automotive tyres and tubes.
- 2. AGMARK is a quality Certification Mark issued by the Food and Agriculture Organisation (FAO).
Which of the statements given above is/are correct ?
Answer (a) & explanation
Only statement 1 is correct (a). The BIS Standard Mark (ISI) is mandatory for certain products through Quality Control Orders, including automotive tyres and tubes, cement, LPG cylinders, electrical appliances and packaged water (1). Statement 2 is wrong because AGMARK is not issued by the FAO. It is India's own mark for farm products such as ghee, honey, spices and pulses. It is given by the Directorate of Marketing and Inspection under the Agricultural Produce (Grading and Marking) Act, 1937.
BIS got statutory status under the BIS Act, 1986, replaced by the 2016 Act. Notice the other quality marks: Hallmark (gold, mandatory since 2021), FPO (processed fruit), Ecomark and FSSAI licensing.
Answer as per the official UPSC answer key.
With reference to ‘Indian Ocean Dipole (IOD)’ sometimes mentioned in the news while forecasting Indian monsoon, which of the following statements is/are correct ?
- 1. IOD phenomenon is characterised by a difference in sea surface temperature between tropical Western Indian Ocean and tropical Eastern Pacific Ocean.
- 2. An IOD phenomenon can influence an El Nino’s impact on the monsoon.
Select the correct answer using the code given below :
Answer (b) & explanation
Only statement 2 is correct (b). Statement 1 is wrong because the Indian Ocean Dipole is the difference in sea-surface temperature between the western Indian Ocean (Arabian Sea, off Africa) and the eastern Indian Ocean (near Sumatra–Java), not the Pacific. In a positive IOD, the western waters are warmer, which brings more rain to India. Statement 2 is right because a positive IOD can offset El Niño's drying effect. In 1997, a strong El Niño year, the monsoon was still normal.
A positive IOD also fuelled the strong 2019 monsoon and the Australian bushfires. Notice the related term ENSO: El Niño (a warm Pacific) usually weakens the monsoon, while La Niña strengthens it. The IMD watches both when forecasting.
Answer as per the official UPSC answer key.