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 is not a bird ?
Answer (a) & explanation
The golden mahseer is not a bird (a). The golden mahseer (Tor putitora) is a large freshwater fish of fast-flowing Himalayan rivers, called the "tiger of the water" by anglers. It is listed as Endangered on the IUCN Red List, hit by dams, sand mining and overfishing. The Indian nightjar (b) is a night bird known for its call. The spoonbill (c) is a wading bird with a flat, spoon-shaped bill. The white ibis (d) is a wading bird with a long, curved bill.
Notice that the golden mahseer is the state fish of Uttarakhand, Himachal Pradesh and J&K. UPSC often mixes fish into bird lists. Spoonbills and ibises gather at Bharatpur (Keoladeo National Park).
Answer as per the official UPSC answer key.
Which one of the following best describes the term “greenwashing” ?
Answer (a) & explanation
Greenwashing means falsely claiming to be eco-friendly (a). Greenwashing is making misleading green claims about a product, a fund or a company, so it looks more environmentally sound than it is. Examples include vague labels like "natural", hiding a small green line behind a dirty core business, or selling an "ESG" fund full of polluters. Option (b) describes the lack of green accounting in national accounts. Option (c) describes careless development, not marketing. Option (d) describes the opposite of greenwashing: building environmental costs into projects.
Notice that regulators now act against it. SEBI set rules for ESG funds, the EU adopted rules on green claims, and India's CCPA issued guidelines on greenwashing in 2024 under the Consumer Protection Act.
Answer as per the official UPSC answer key.
A bill for ₹ 1,840 is paid in the denominations of ₹ 50, ₹ 20 and ₹ 10 notes. 50 notes in all are used. Consider the following statements :
- 1. 25 notes of ₹ 50 are used and the remaining are in the denominations of ₹ 20 and ₹ 10.
- 2. 35 notes of ₹ 20 are used and the remaining are in the denominations of ₹ 50 and ₹ 10.
- 3. 20 notes of ₹ 10 are used and the remaining are in the denominations of ₹ 50 and ₹ 20.
Which of the above statements are not correct?
Answer (d) & explanation
1. a + b + c = 50 and 50a + 20b + 10c = 1840. Subtract 10 × the first: 4a + b = 134.
2. 1: a = 25 gives b = 34, but then c = –9. Impossible. 2: b = 35 needs 4a = 99. Not a whole number.
3. 3: c = 20 gives a + b = 30 and 4a + b = 134, so a = 34·67. Impossible. All three are not correct.
the question asks which are not correct.
Answer as per the official UPSC answer key.
Eight students A, B, C, D, E, F, G and H sit around a circular table, equidistant from each other, facing the centre of the table, not necessarily in the same order. B and D sit neither adjacent to C nor opposite to C. A sits in between E and D, and F sits in between B and H. Which one of the following is definitely correct?
Answer (d) & explanation
None of the options is definitely correct (d). Step 1: the blocks are E–A–D and B–F–H. C must not sit next to or opposite B or D. Step 2: several seatings meet all the rules. For example, going round: A, D, G, C, H, F, B, E. Step 3: in this seating, B is not between A and G (a fails), C is not opposite G (b fails) and E is not opposite F (c fails). Since one valid seating breaks each option, none is definite.
Tip: for "definitely correct", find one valid arrangement that breaks the option. One counter-example is enough to reject it.
'definitely correct' means true in every possible seating. One valid seating where it fails is enough to reject it.
Answer as per the official UPSC answer key.
Read the passage
To encourage research is one of the functions of a university. Contemporary universities have encouraged research, not only in those cases where research is necessary, but on all sorts of entirely unprofitable subjects as well. Scientific research is probably never completely valueless. However silly and insignificant it may seem, however mechanical and unintelligent the labours of the researchers, there is always a chance that the results may be of value to the investigator of talent, who can use the facts collected for him by uninspired but industrious researchers as the basis of some fruitful generalization. But where research is not original, but consists in the mere rearrangement of existing materials, where its object is not scientific but literary or historical, then there is a risk of the whole business becoming merely futile.
According to the author
Answer (c) & explanation
Any research result can be of value to an intelligent investigator (c). Step 1: the passage says "there is always a chance that the results may be of value" to a talented investigator. Step 2: "chance" and "may" mean any result can help. That is (c). Step 3: options (b) and (d) turn a chance into a certainty ("always valuable", "must always be"). Option (a), not many results are useful, goes against the passage.
Tip: words like "may", "chance" and "can" signal possibility. Reject options that turn possibility into certainty.
Answer as per the official UPSC answer key.
The term “Levant” often heard in the news roughly corresponds to which of the following regions ?
Answer (a) & explanation
The Levant is the eastern Mediterranean shore (a). The word Levant comes from the French for "rising", meaning the lands where the sun rises, seen from Europe. It covers the eastern Mediterranean coast: Syria, Lebanon, Israel, Palestine and Jordan, sometimes with Cyprus and southern Turkey. Option (b) describes the Maghreb plus Egypt, the North African coast. Option (c) describes the Gulf and the Horn of Africa, which are far to the south-east. Option (d) is too wide: the whole Mediterranean coast includes Europe and North Africa.
Notice that ISIS was also called ISIL, the "L" standing for the Levant. The region is in the news for the Gaza war since October 2023, and for India's proposed IMEC corridor through it.
Answer as per the official UPSC answer key.
With reference to Indian history, consider the following statements :
- 1. The Dutch established their factories/warehouses on the east coast on lands granted to them by Gajapati rulers.
- 2. Alfonso de Albuquerque captured Goa from the Bijapur Sultanate.
- 3. The English East India Company established a factory at Madras on a plot of land leased from a representative of the Vijayanagara empire.
Which of the statements given above are correct ?
Answer (b) & explanation
Statements 2 and 3 are correct (b). Statement 2 is right: Afonso de Albuquerque captured Goa from the Bijapur Sultanate in 1510, and it became the capital of Portuguese India. Statement 3 is right: Francis Day got the site of Madras in 1639 from Damarla Venkatadri Nayaka, a nayaka under the Vijayanagara (Chandragiri) ruler; Fort St George came up there. Statement 1 is wrong: the Dutch got Masulipatnam (1605) from Golconda and Pulicat from the Vijayanagara side. The Gajapati kingdom of Odisha had already fallen by then.
Notice the order of arrival: Portuguese (1498), English EIC (1600), Dutch VOC (1602), Danes (1616) and French (1664). The Dutch made Pulicat and later Nagapatnam their Coromandel headquarters.
Answer as per the official UPSC answer key.
Consider the following pairs :
| King | Dynasty
| 1. Nannuka | Chandela
| 2. Jayashakti | Paramara
| 3. Nagabhata II | Gurjara-Pratihara
| 4. Bhoja | Rashtrakuta
How many pairs given above are correctly matched ?
Answer (b) & explanation
Two pairs are correctly matched (b). Pair 1 is right: Nannuka founded the Chandela dynasty of Bundelkhand in the 9th century. Pair 3 is right: Nagabhata II was the Gurjara-Pratihara king who captured Kanauj in about 816. Pair 2 is wrong: Jayashakti (Jeja) was a Chandela, not a Paramara; the region Jejakabhukti is named after him. Pair 4 is wrong: Bhoja points to Mihira Bhoja of the Pratiharas or Raja Bhoja of the Paramaras of Malwa, never a Rashtrakuta.
Notice the tripartite struggle for Kanauj among the Pratiharas, Palas and Rashtrakutas in the 8th–10th centuries. The Chandelas are best known for building Khajuraho.
Answer as per the official UPSC answer key.
Consider the Question and two Statements given below :
Question : Is x an integer?
Statement-1 : x/3 is not an integer.
Statement-2 : 3x is an integer.
Which one of the following is correct in respect of the Question and the Statements?
Answer (d) & explanation
Even both statements together are not enough (d). Step 1: test a value that fits both statements: x = 1. Then 1/3 is not an integer, and 3 × 1 = 3 is an integer. Here x is an integer. Step 2: test x = 1/3. Then 1/9 is not an integer, and 3 × 1/3 = 1 is an integer. Here x is not an integer. Step 3: both statements hold in each case, but the answer differs. So they are not sufficient. Options (a), (b) and (c) fail.
Tip: in data sufficiency, try fractions and negative numbers too. Two allowed values giving different answers prove the data insufficient.
in this older format, (d) means "even together not sufficient".
Answer as per the official UPSC answer key.
Read the passage
In an economic organization, allowing mankind to benefit by the productivity of machines should lead to a very good life of leisure, and much leisure is apt to be tedious except to those who have intelligent activities and interests. If a leisured population is to be happy, it must be an educated population, and must be educated with a view to enjoyment as well as to the direct usefulness of technical knowledge.
Which of the following statements best reflects the underlying tone of the passage?
Answer (a) & explanation
The underlying tone is that only an educated population can best use the benefits of economic progress (a). Step 1: the passage says machines can give people much leisure, but leisure is tedious except for those with intelligent interests. Step 2: so a happy leisured population "must be an educated population". Education turns progress into a good life. That is (a). Step 3: option (c) turns this into a general rule that more education always means more happiness, which is not said. Options (b) and (d) make leisure the aim, which the passage does not argue.
Tip: this is from Bertrand Russell. Pick the option that keeps the passage's condition ("must be educated"), not one that reverses it.
Answer as per the official UPSC answer key.
With reference to the Indian economy, consider the following statements :
- 1. If the inflation is too high, Reserve Bank of India (RBI) is likely to buy government securities.
- 2. If the rupee is rapidly depreciating, RBI is likely to sell dollars in the market.
- 3. If interest rates in the USA or European Union were to fall, that is likely to induce RBI to buy dollars.
Which of the statements given above are correct ?
Answer (b) & explanation
Statements 2 and 3 are correct (b). Statement 1 is wrong: to fight high inflation, the RBI sells government securities through open market operations, pulling money out of the system; buying them would add money. Statement 2 is right: to stop the rupee falling fast, the RBI sells dollars from its forex reserves, which raises the supply of dollars. Statement 3 is right: when US or EU interest rates fall, foreign money flows into India and the rupee tends to rise, so the RBI buys dollars to smooth this and add to reserves.
Notice sterilisation: when the RBI buys dollars it releases rupees, so it may sell bonds to soak them up. India's forex reserves crossed $700 billion in 2024.
statement 1 has the right tool but the wrong direction. Always ask: does this action add money or remove it?
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. Biofilms can form on medical implants within human tissues.
- 2. Biofilms can form on food and food processing surfaces.
- 3. Biofilms can exhibit antibiotic resistance.
Which of the statements given above are correct ?
Answer (d) & explanation
All three statements are correct (d). A biofilm is a colony of microbes stuck to a surface inside a slimy matrix they make themselves. Statement 1 is right: biofilms form on catheters, artificial joints and other medical implants, causing hard-to-treat infections. Statement 2 is right: they form on food and food-processing surfaces, spreading germs such as Listeria. Statement 3 is right: the matrix shields the bacteria, making them far more resistant to antibiotics, sometimes 1,000 times more.
Notice the everyday example: dental plaque is a biofilm. Biofilms also clog pipes and harm ship hulls. They add to the problem of antimicrobial resistance, which the WHO lists among the top global health threats.
Answer as per the official UPSC answer key.
Consider the following pairs :
| Reservoirs | States
| 1. Ghataprabha | Telangana
| 2. Gandhi Sagar | Madhya Pradesh
| 3. Indira Sagar | Andhra Pradesh
| 4. Maithon | Chhattisgarh
How many pairs given above are not correctly matched ?
Answer (c) & explanation
Three pairs are wrongly matched (c). Pair 2 is the only correct one: Gandhi Sagar dam on the Chambal is in Madhya Pradesh. Pair 1 is wrong: Ghataprabha reservoir (Hidkal dam) on the Ghataprabha river, a tributary of the Krishna, is in Karnataka, not Telangana. Pair 3 is wrong: Indira Sagar on the Narmada is also in Madhya Pradesh; it has India's largest reservoir by storage. Pair 4 is wrong: Maithon, a Damodar Valley Corporation dam on the Barakar river, is in Jharkhand, near the West Bengal border, not Chhattisgarh.
Notice that the Chambal has three dams in a row: Gandhi Sagar (MP), Rana Pratap Sagar and Jawahar Sagar (Rajasthan). Together with the Kota barrage, they form one scheme.
The question asks how many are not correctly matched. Count the wrong pairs.
Answer as per the official UPSC answer key.
With reference to the writs issued by the Courts in India, consider the following statements :
- 1. Mandamus will not lie against a private organisation unless it is entrusted with a public duty.
- 2. Mandamus will not lie against a Company even though it may be a Government Company.
- 3. Any public minded person can be a petitioner to move the Court to obtain the writ of Quo Warranto.
Which of the statements given above are correct?
Answer (d) & explanation
All three statements are correct (d). Statement 1 is right: mandamus commands a body to perform a public duty, so it does not lie against a private organisation unless that body has been given a public duty. Statement 2 is right per the key: in Praga Tools (1966), the Supreme Court held that mandamus does not lie against a company, even a government company, unless a public duty is involved. Statement 3 is right: for quo warranto, which asks "by what authority" someone holds a public office, the petitioner need not be personally affected; any member of the public can apply.
Notice the five writs: habeas corpus, mandamus, prohibition, certiorari and quo warranto, under Articles 32 and 226. High Courts can issue writs for any legal right.
statement 2 sounds wrong because a government company feels "public". UPSC followed the line in Praga Tools.
UPSC repeats traps like this year after year. The PYQ Book gathers every trap in one place, so you see them coming. Try the free sample
Answer as per the official UPSC answer key.
Three persons A, B and C are standing in a queue not necessarily in the same order. There are 4 persons between A and B, and 7 persons between B and C. If there are 11 persons ahead of C and 13 behind A, what could be the minimum number of persons in the queue?
Answer (a) & explanation
The minimum is 22 persons (a). Step 1: 11 people are ahead of C, so C is 12th. Step 2: 7 people stand between B and C. So B is 4th or 20th. To keep the queue short, take B = 4th. Step 3: 4 people stand between A and B. A cannot be before 1st, so A is 9th. 13 people are behind A, so the queue has 9 + 13 = 22. C at 12th lies inside it. Options (b), (c) and (d) come from other, longer placements.
Tip: for a minimum, place people as close to the front as the rules allow, then check every condition.
Taking B = 20th pushes A to 15th or 25th and gives 28 or more.
Answer as per the official UPSC answer key.
Read the passage
The majority of people who fail to accumulate money sufficient for their needs, are generally, easily influenced by the opinions of others. They permit the newspapers and the gossiping neighbours to do their thinking for them. Opinions are the cheapest commodities on the earth. Everyone has a flock of opinions ready to be wished upon by anyone who will accept them. If you are influenced by opinions when you reach decisions, you will not succeed in any undertaking.
What is the main idea of the passage?
Answer (a) & explanation
The main idea is that people should not be influenced by others' opinions (a). Step 1: the passage says people who fail to save let newspapers and neighbours think for them. Opinions are "the cheapest commodities". Step 2: it ends: if opinions influence your decisions, "you will not succeed". So don't be swayed by them. That is (a). Step 3: option (b), save as much as you can, is not the point. Option (c) says never give or take opinions, which goes too far. Option (d) turns the warning into a guarantee of success.
Tip: "If you do X, you will fail" does not mean "If you avoid X, you will succeed". Watch for this reversal trap.
Answer as per the official UPSC answer key.
Which of the following is/are the exclusive power(s) of Lok Sabha?
- 1. To ratify the declaration of Emergency
- 2. To pass a motion of no-confidence against the Council of Ministers
- 3. To impeach the President of India
Select the correct answer using the code given below :
Answer (b) & explanation
Only the no-confidence motion is exclusive to the Lok Sabha (b). Item 2 is right: under Article 75(3), the Council of Ministers is collectively responsible to the Lok Sabha, so only it can pass a no-confidence motion and remove the government. Item 1 is wrong: an Emergency proclamation must be approved by both Houses within one month, by a special majority. Item 3 is wrong: impeachment of the President under Article 61 needs both Houses: one House frames the charge and the other investigates it.
Notice other Lok Sabha-only powers: Money Bills start only there (Article 110), and it alone can reject or reduce demands for grants. The Rajya Sabha's exclusive powers are under Articles 249 and 312.
revoking an Emergency is the Lok Sabha's alone (Article 352(7)), but approving it needs both Houses.
Answer as per the official UPSC answer key.
Which of the following are nitrogen-fixing plants ?
- 1. Alfalfa
- 2. Amaranth
- 3. Chickpea
- 4. Clover
- 5. Purslane (Kulfa)
- 6. Spinach
Select the correct answer using the code given below:
Answer (a) & explanation
Alfalfa, chickpea and clover fix nitrogen (a). Nitrogen fixing is done by Rhizobium bacteria living in the root nodules of legumes, which turn nitrogen from the air into forms plants can use. Item 1 is right: alfalfa (lucerne) is a legume fodder crop. Item 3 is right: chickpea (gram) is a legume. Item 4 is right: clover is a legume. Items 2, 5 and 6 are wrong: amaranth, purslane (kulfa) and spinach are leafy plants of other families and fix no nitrogen.
Notice why farmers grow legumes in crop rotation: they enrich the soil and cut the need for urea. Nitrogen is also fixed by free-living microbes such as Azotobacter and cyanobacteria, used as biofertilisers in paddy fields.
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. High clouds primarily reflect solar radiation and cool the surface of the Earth.
- 2. Low clouds have a high absorption of infrared radiation emanating from the Earth’s surface and thus cause warming effect.
Which of the statements given above is/are correct ?
Answer (d) & explanation
Neither statement is correct (d). The roles are reversed. Statement 1 is wrong: thin, icy high clouds such as cirrus let most sunlight pass through but trap the outgoing infrared heat from the Earth, so on balance they warm the surface. Statement 2 is wrong: thick, bright low clouds such as stratocumulus reflect a lot of incoming sunlight back to space, so on balance they cool the surface. Low clouds are warm, close to the ground, and give off almost as much heat as the surface does, so their trapping effect is small.
Notice why this matters for climate: cloud changes are the biggest uncertainty in climate models. This is also why cloudy nights stay warmer than clear nights, when heat escapes freely.
Answer as per the official UPSC answer key.
Which number amongst 240, 321, 418 and 812 is the smallest?
Answer (b) & explanation
3²¹ is the smallest (b). Step 1: write the powers of 2, 4 and 8 in base 2. 4¹⁸ = 2³⁶ and 8¹² = 2³⁶. So (c) and (d) are equal, and both are smaller than 2⁴⁰ (a). Step 2: compare 3²¹ with 2³⁶. Make the powers equal: 3²¹ = (3⁷)³ = 2187³, and 2³⁶ = (2¹²)³ = 4096³. Step 3: 2187 is less than 4096, so 3²¹ is the smallest. Options (a), (c) and (d) are larger.
Tip: to compare powers, change them to the same base or the same exponent. Also note that two equal options can never be "the smallest" alone.
Answer as per the official UPSC answer key.