UPSC Prelims PYQs with explanations
Real questions from official papers, mapped to syllabus topics. Attempt each one; the answer and the reason appear instantly.
Which of the following countries are members of the European Union ?
- 1. Belarus
- 2. Poland
- 3. Germany
- 4. Switzerland
Select the answer using the code given below :
Answer (c) & explanation
Poland and Germany are EU members (c). Item 2 is right: Poland joined in the big 2004 enlargement. Item 3 is right: Germany is a founder member from the 1957 Treaty of Rome. Item 1 is wrong: Belarus is close to Russia and not in the EU. Item 4 is wrong: Switzerland stays outside, linked through bilateral deals and the Schengen area. So options (a), (b) and (d) fail.
Notice the numbers: the EU has 27 members since the UK left (Brexit, 2020). Norway, Iceland and Liechtenstein are in the European Economic Area but not the EU. India and the EU concluded talks on their Free Trade Agreement in January 2026.
Answer as per the official UPSC answer key.
Question : If x and y are integers, then is x even?
Statement I : x2y2 is even.
Statement II : 1 + x2 + y2 is odd.
Answer (c) & explanation
Both statements together are needed (c). Step 1: Statement I: x²y² is even, so xy is even. That means at least one of x and y is even. x might be odd if y is even. Not enough. Step 2: Statement II: 1 + x² + y² is odd, so x² + y² is even. That means x and y have the same parity (both odd or both even). Not enough. Step 3: together: same parity, and at least one even, so both are even. Hence x is even. Options (a), (b) and (d) fail.
Tip: remember odd + odd = even, even + even = even, odd + even = odd. A square keeps the parity of its number.
Answer as per the official UPSC answer key.
Seven persons A, B, C, D, E, F and G travel by three cars X, Y, Z. A and another two of them travel by X. Only E travels with G. C travels by Z, but B does not travel by Y. Besides, A and B do not travel by the same car. Then which of the following are correct?
- I. No one travels alone.
- II. Only D travels with F.
- III. Only C travels with B.
Select the answer using the code given below.
Answer (b) & explanation
1. B is not in Y and not with A (in X), so B is in Z with C.
2. E and G form a car of their own; X already has A and Z has B and C, so E and G are in Y. D and F join A in X.
3. Cars: X = A, D, F; Y = E, G; Z = B, C. I and III are true. II is false, because A also travels with F.
Answer as per the official UPSC answer key.
If ZERO is encoded as ADSN, then how do you encode STOP?
Answer (b) & explanation
STOP is encoded as TSPO (b). Step 1: compare ZERO and ADSN letter by letter: Z → A (+1, wrapping round), E → D (−1), R → S (+1), O → N (−1). The moves alternate +1, −1. Step 2: apply to STOP: S + 1 = T, T − 1 = S, O + 1 = P, P − 1 = O. Step 3: so STOP becomes TSPO. Options (a) SPOT, (c) TSOP and (d) POST are rearrangements that do not follow the rule.
Tip: in letter codes, write the shift for each position. Remember that after Z comes A again. Options that are real words are often traps.
Answer as per the official UPSC answer key.
Consider the following statements with reference to India’s response to climate change :
- I. India’s Long-Term Low Emission Development Strategy (LT-LEDS) is a crucial tool for achieving net-zero emissions by 2070.
- II. India’s 4th Biennial Update Report (BUR-4) submitted in December, 2024 recorded around 8% decrease in Greenhouse gas emissions in 2020 over 2019.
- III. Climate-resilient development necessarily depends on quick and short-term achievement of emission reduction targets.
Which of the following relationships among the above statements is/are correct ?
- 1. Statement I is empirically supported by statement II.
- 2. Statement III contradicts the approach implicit in statement I.
- 3. Statement I and statement III together establish the premise of long-term sustainability.
Select the answer using the code given below :
Answer (b) & explanation
Relationships 1 and 2 are correct (b). Relationship 1 is right: the LT-LEDS (2022) lays out India's path to net zero by 2070, and BUR-4 reported a fall of about 7.9% in 2020 emissions over 2019, real data in line with that path. Relationship 2 is right: Statement III wants quick, short-term cuts, while the LT-LEDS is a long, gradual plan, so III contradicts I. Relationship 3 is wrong: two contradicting statements cannot together set a premise. So options (a), (c) and (d) fail.
Notice the cause of the 2020 fall: the COVID-19 lockdowns, not a lasting trend. India's updated NDC (2022) targets cutting emissions intensity of GDP by 45% from 2005 levels by 2030. Biennial Transparency Reports now replace BURs.
"together establish" sounds positive, but two statements that clash cannot form one premise.
Answer as per the official UPSC answer key.
Ms. X is a mid-level civil service official working in the urban development department of a major city. Recently, she was involved in approving a contract for a public infrastructure project — a new community park. During the approval process, she received a piece of confidential information indicating that one of the shortlisted contractors had a history of poor workmanship and allegations of corruption in other cities, though nothing had been legally proven. The Head of the Department, Mr. Y, advised her not to disclose this information to the project committee or the public because it could delay the project and damage the city's reputation. However, Ms. X believed that withholding such information compromised transparency and public trust.
What amongst the following should Ms. X do now ?
- 1. Immediately disclose the information to the project committee and the public
- 2. Recommend removing the contractor from the shortlist to protect the project's integrity
- 3. Propose a 'limited disclosure' to an oversight committee, while keeping the information confidential from the public for the time being
Select the answer using the code given below :
Answer (b) & explanation
Only action 3 is right (b). The information is confidential and the charges are not proven. Action 3 is right: a limited disclosure to an oversight committee lets the proper authority check the facts while protecting both the process and a firm that may be innocent. Action 1 is wrong: making unproven charges public at once can damage reputations unfairly and break confidentiality. Action 2 is wrong: striking the contractor off on her own punishes without a finding. So options (a), (c) and (d) fail.
Notice the balance being tested: transparency versus due process. Ms. X also rightly refuses her senior's advice to hide the matter, because silence would hurt public trust. Ethics answers usually favour the proper channel over both cover-up and public exposure.
"unproven allegation" is the key phrase. Public disclosure and instant punishment both jump ahead of the facts.
Answer as per the official UPSC answer key.
Which of the following statements regarding the features of blockchain technology are correct ?
- 1. Records stored in the database may be made visible to relevant stakeholders without risk of alteration.
- 2. Copies of the entire database are stored on multiple computers on a network, syncing within seconds.
- 3. Consortium blockchain is a blend of public and private blockchains allowing selective data access.
- 4. Mathematical algorithms make it impossible to change or delete any data once recorded and accepted.
Select the answer using the code given below :
Answer (c) & explanation
Statements 1, 2 and 4 are correct (c). A blockchain is a shared record of transactions copied across many computers. Statement 1 is right: records can be shown to stakeholders without risk of alteration. Statement 2 is right: copies of the whole ledger sit on many nodes and sync quickly. Statement 4 is right: cryptographic hashing links each block to the last, so accepted data cannot be changed or deleted. Statement 3 is wrong: a blend of public and private is a hybrid blockchain; a consortium blockchain is run by a group of organisations. So options (a), (b) and (d) fail.
Notice uses in India: land records, supply chains, and the RBI's e-rupee pilots. Bitcoin (2009) was the first public blockchain.
Consortium and hybrid both sound like a mix. Consortium means many owners; hybrid means a mix of public and private.
Answer as per the official UPSC answer key.
Eight persons P, Q, R, S, T, U, V and W sit around a round table in eight different seats placed with equal distance between any two consecutive seats. Both P and R are adjacent to Q. Both T and R are adjacent to S. Both U and W are adjacent to V. S and W are on opposite chairs. If while going in the clockwise direction around the table from P, one meets R before T, then how many persons shall Q cross while moving in the clockwise direction around the table before meeting W?
Answer (a) & explanation
1. P–Q–R and R–S–T join into one run P, Q, R, S, T. Clockwise from P, R comes before T, so number the seats 1 to 8 clockwise: P 1, Q 2, R 3, S 4, T 5.
2. U, V, W take seats 6, 7, 8 with V in the middle (seat 7). W must face S (seat 4), so W is at seat 8 and U at 6.
3. Clockwise from Q: R, S, T, U, V, then W. Q crosses 5 persons.
Answer as per the official UPSC answer key.
Read the passage
The key source of the battle for clean skies and clear lungs is the fuel we burn—from household Chulhas to the thermal power plants. In most cases, it is biomass or coal. The Supreme Court banned the use of pet coke—the dirtiest of such fuels. The Delhi Government banned the use of coal, which was later extended to the entire National Capital Region. It was also agreed that the thermal power plants would clean up or shut down. Action on this has been patchy to say the least. The lesson from the transition to CNG is that people need alternatives for a ban to be effective. When diesel buses were stopped, CNG supply had to be assured. It also had to be feasible in terms of cost. The Supreme Court agreed that fiscal measures were needed to keep clean fuel cheaper than dirty fuel. Now even as coal is banned, the price of natural gas makes industry uncompetitive.
Which of the following inferences is/are correct?
- 1. The source of the energy we consume is the key to the battle for cleaner air.
- 2. Bans are effective where the will is strong and the people are convinced that such bans are for the greater good of society.
- 3. There is judicial approval for a policy that intervenes fiscally to facilitate benevolent pricing for cleaner fuel.
Select the answer using the code given below.
Answer (c) & explanation
Inferences 1 and 3 are correct (c). Step 1: the passage opens: the key to clean skies is "the fuel we burn". So the source of energy is central (1). Step 2: it says "the Supreme Court agreed that fiscal measures were needed to keep clean fuel cheaper than dirty fuel". That is judicial approval for pricing help (3). Step 3: inference 2 says bans work when people are convinced they are for the greater good. But the passage says bans work when people have alternatives at a feasible cost, like CNG. So options (a), (b) and (d) fail.
Tip: find the passage's own reason; do not accept a different reason that sounds good. Delhi's switch of buses to CNG followed Supreme Court orders around 2001–02.
Answer as per the official UPSC answer key.
Three partners A, B and C entered into a business. A invested one-third of the capital for one-third duration. B invested one-fourth of the capital for one-fourth duration. C invested the remaining capital for the whole duration. Out of a profit of ₹ 17,000, how much profit will C get?
Answer (a) & explanation
C gets ₹12,000 (a). Step 1: profit is shared in the ratio of capital × time. A: 1/3 of capital for 1/3 of the time = 1/9. B: 1/4 for 1/4 = 1/16. C put in the rest: 1 − 1/3 − 1/4 = 5/12, for the whole time = 5/12. Step 2: multiply by 144 to clear fractions: A : B : C = 16 : 9 : 60. Total = 85 parts. Step 3: C's share = 60/85 × 17,000 = ₹12,000. Options (b), (c) and (d) fail.
Tip: in partnerships, multiply capital by time for each partner. Clear fractions with the LCM of the denominators before sharing.
Answer as per the official UPSC answer key.
With reference to Madhav National Park, which of the following statements is/are correct ?
- 1. It was declared a Tiger Reserve in India in 2025.
- 2. Sakhya Sagar, which is designated as a Ramsar Site, is situated within this National Park.
- 3. Its area is shared between Madhya Pradesh and Rajasthan.
Select the answer using the code given below :
Answer (b) & explanation
Statements 1 and 2 are correct (b). Statement 1 is right: Madhav National Park in Shivpuri district became India's 58th tiger reserve in March 2025. Statement 2 is right: Sakhya Sagar lake inside it was named a Ramsar site in 2022. Statement 3 is wrong: the park lies wholly in Madhya Pradesh, not shared with Rajasthan. So options (a), (c) and (d) fail.
Notice MP's place as the "Tiger State", with the most tigers and nine reserves, including Kanha, Bandhavgarh, Pench and Panna. The NTCA approves tiger reserves under the Wild Life (Protection) Act. Kuno, also in MP, is home to India's reintroduced cheetahs. India has about 75% of the world's wild tigers.
Shivpuri is near the Rajasthan border, which makes "shared" sound believable.
Answer as per the official UPSC answer key.
Consider the following statements with respect to the AI Impact Summit, 2026 held in New Delhi :
- 1. The Summit’s intellectual framework was based on three foundational Sutras : People, Planning, and Progress.
- 2. The Preamble of the Summit stresses Democratising AI Resources, which acknowledges the Charter for Democratic Diffusion of AI as a binding framework to support locally relevant innovation and strengthen resilient AI ecosystems while respecting national laws.
- 3. The New Delhi Declaration on AI Impact was structured around seven Chakras (Pillars), which included Access for Social Empowerment, AI for Science, and Secure and Trusted AI.
Which of the statements given above is/are correct ?
Answer (d) & explanation
Only statement 3 is correct (d). Statement 3 is right: the New Delhi Declaration on AI Impact was built around seven chakras (pillars), including access for social empowerment, AI for science and secure and trusted AI. Statement 1 is wrong: the three sutras were People, Planet and Progress, not "Planning". Statement 2 is wrong: the Charter for Democratic Diffusion of AI is voluntary, not binding. So options (a), (b) and (c) fail.
Notice the event: the AI Impact Summit was held at Bharat Mandapam, New Delhi, in February 2026, the first global AI summit in the Global South. It followed the summits at Bletchley Park (2023), Seoul (2024) and Paris (2025). At home, the IndiaAI Mission (2024) funds shared GPU computing.
Statement 1 changes one word, Planet to Planning. Statement 2 changes voluntary to binding.
Answer as per the official UPSC answer key.
Which of the following statements about Crowdfunding is/are correct ?
- 1. Crowdfunding is solicitation of funds (small amount) from multiple investors through a web-based platform or social networking site for a specific project.
- 2. Small and Medium Enterprises (SMEs) are able to raise funds at lower cost of capital without undergoing rigorous procedures.
Select the answer using the code given below :
Answer (c) & explanation
Both statements are correct (c). Statement 1 is right: crowdfunding means raising small sums from many investors through an online platform or social media for a specific project. Statement 2 is right: it lets start-ups and SMEs raise money at a lower cost and with fewer procedures than a bank loan or public issue. Both lines come almost word for word from SEBI's 2014 consultation paper. So options (a), (b) and (d) fail.
Notice the types: donation-based (like Ketto for medical bills), reward-based, debt-based (peer-to-peer lending, regulated by the RBI since 2017), and equity-based. SEBI has not yet allowed equity crowdfunding in India, warning platforms against it.
Answer as per the official UPSC answer key.
The class average x in a test increases by 4 when the score of a student is rectified, whose corrected score is 100 instead of 0. Later, the score of another student was found to have been recorded as 81 in place of 56. If there are no other corrections and the final corrected average is y, then y − x is
Answer (b) & explanation
y − x is 3 (b). Step 1: one student's score rose by 100 (from 0 to 100), and the average rose by 4. So the class has 100 ÷ 4 = 25 students. Step 2: the second correction changes 81 to 56: the total falls by 25 marks. Shared by 25 students, the average falls by 1. Step 3: overall, the average went up by 4 and then down by 1: y − x = 3. Options (a), (c) and (d) fail.
Tip: change in average = change in total ÷ number of people. Use the first correction to find the class size, then reuse it.
x is the average before both corrections, so both changes count.
Answer as per the official UPSC answer key.
In a sequence of numbers, each number other than the first two is the sum of the two immediately preceding numbers from it. If the first two numbers in the sequence are 4 and 7, then the sixth number is
Answer (d) & explanation
The sixth number is 47 (d). Step 1: the rule: each number after the first two is the sum of the two before it. Step 2: start with 4 and 7. Third: 4 + 7 = 11. Fourth: 7 + 11 = 18. Fifth: 11 + 18 = 29. Step 3: sixth: 18 + 29 = 47. Option (a), 29, is the fifth number, a common slip from miscounting positions. Options (b) and (c) are wrong sums.
Tip: this is a Fibonacci-style sequence. Write out every term and number its position so you do not stop one step early. The classic Fibonacci series starts 1, 1, 2, 3, 5, 8.
Answer as per the official UPSC answer key.
Consider the following statements about the Rigvedic period :
- I. Irrigation from wells allowed agriculture to expand away from flood plains and strips on river margins into the present Punjab and Haryana plains having underground water levels reasonably close to the surface.
- II. Draught-animal power was employed to draw up water out of the wells.
Which of the following information support/supports the above statements ?
- 1. There is evidence in the Rigveda of the use of ashma chakra (stone pulley wheel) and ahava (strapped wooden pails) to draw up water.
- 2. Mention has been made in the Rigveda of the use of implements like parashu/ kulisha (axe) and datra /sreni (sickle).
- 3. There is a history of the use of ox, even before the Rigveda, for ploughing the land and pulling the carts.
Select the answer using the code given below :
Answer (c) & explanation
Information 1 and 3 support the statements (c). Item 1 is right: the ashma chakra (stone pulley wheel) and ahava (strapped wooden pails) of the Rigveda show water being lifted from wells, which supports Statement I. Item 3 is right: the ox was already used for ploughing and pulling carts before the Rigveda, so animal power was available to lift water, which supports Statement II. Item 2 is wrong: axes and sickles are farm tools, but they say nothing about wells or irrigation.
Notice the method: in such questions, ask whether each fact directly supports the claim, not just whether it is true. The Rigvedic economy was mainly pastoral, with cattle as wealth (gavishti, the search for cows, meant war). Iron and big farming came later.
Statement 2 is true, but it does not support either statement. "Supports" questions test relevance, not truth.
Answer as per the official UPSC answer key.
Which of the following statements with regard to stealth technology is/are correct ?
- 1. Stealth objects have a very small radar cross-section and are coated with Radar Absorbing Material.
- 2. Stealth objects can be detected using specific frequencies.
- 3. Stealth objects are coated with metamaterials to increase the scattering of electromagnetic radiation.
Select the answer using the code given below :
Answer (c) & explanation
Statements 1 and 2 are correct (c). Statement 1 is right: stealth aircraft cut their radar cross-section through shape and radar-absorbing material (RAM). Statement 2 is right: they are tuned against common radar bands, so low-frequency radars, such as VHF, can still pick them up. Statement 3 is wrong: metamaterial coatings are meant to absorb or bend waves away, reducing the echo, not increasing scattering. So options (a), (b) and (d) fail.
Notice examples: the US F-35 and B-2, China's J-20, and Russia's Su-57. India's AMCA fifth-generation fighter is planned to be stealthy. Stealth also cuts infrared heat and noise signatures. Other counters include passive radar and multi-static radar networks.
Statement 3 uses a real term, metamaterials, but gives them the opposite purpose.
Answer as per the official UPSC answer key.
Match List I with List II and select the answer using the code given below the Lists :
| List I (INTERPOL Notice) | List II (Description)
| A. Silver Notice | 1. To seek information on unidentified bodies
| B. Blue Notice | 2. To collect additional information about a person’s identity, location, or activities in relation to a criminal investigation
| C. Black Notice | 3. To provide warning about a person’s criminal activities, where the person is considered to be a possible threat to public safety
| D. Green Notice | 4. To identify and trace criminal assets
Code :
Answer (c) & explanation
The correct match is A-4, B-2, C-1, D-3 (c). The Silver Notice, first issued in January 2025 as a pilot, helps trace criminal assets (A-4). A Blue Notice collects more information about a person's identity, location or activities (B-2). A Black Notice seeks information on unidentified bodies (C-1). A Green Notice warns about a person's criminal activities when they may threaten public safety (D-3). Options (a), (b) and (d) mix these up.
Notice the best-known one: a Red Notice asks police worldwide to locate and provisionally arrest a person pending extradition. A Yellow Notice helps find missing persons, and an Orange Notice warns of an imminent threat. In India, the CBI is the National Central Bureau for INTERPOL, which is headquartered in Lyon.
Answer as per the official UPSC answer key.
Question : X is a collection of certain odd numbers whereas Y is a collection of certain even numbers. T consists of the numbers all of which are either from X or from Y. Is every number of T from Y?
Statement I : The sum of any two numbers belonging to T is even.
Statement II : If both p and q are picked from T, then (p – 1)q is even.
Answer (d) & explanation
Even both statements together are not enough (d). Step 1: Statement I: any two numbers in T add to an even number. That happens only if T is all odd or all even. Step 2: Statement II: (p − 1)q is even for any p, q in T. If T is all odd, p − 1 is even, so it holds. If T is all even, q is even, so it holds. Both cases still allowed. Step 3: an all-odd T (from X) fits both statements, and so does an all-even T (from Y). So we cannot say every number is from Y. Options (a), (b) and (c) fail.
Tip: test each statement on both possible cases. If a case survives every statement, the data is not enough.
Answer as per the official UPSC answer key.
There are four statements X, Y, Z and W. Their relations are as follows :
If X is incorrect, then so is Z; if Y is incorrect, then W is correct; if W is correct, then X is incorrect.
Which of the following is/are correct?
- I. If X is correct, then so is Y.
- II. If Z is correct, then it is not necessary that Y is correct.
Select the answer using the code given below.
Answer (a) & explanation
Only statement I is correct (a). Step 1: turn each rule around (the contrapositive, which is always equally true): "X incorrect → Z incorrect" becomes Z correct → X correct. "Y incorrect → W correct" becomes W incorrect → Y correct. "W correct → X incorrect" becomes X correct → W incorrect. Step 2: statement I: X correct → W incorrect → Y correct. So I is true. Step 3: statement II: Z correct → X correct → W incorrect → Y correct. So Y must be correct; II says it is not necessary, which is false. Options (b), (c) and (d) fail.
Tip: "If A then B" also means "if not B then not A". Chaining contrapositives solves most such puzzles.
only the contrapositive of an 'if … then' is safe. Here it links all four statements into one chain.
Answer as per the official UPSC answer key.