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 one of the following protected areas is well-known for the conservation of a sub-species of the Indian swamp deer (Barasingha) that thrives well on hard ground and is exclusively graminivorous ?
Answer (a) & explanation
Kanha protects the hard-ground barasingha (a). The swamp deer has three sub-species. The hard-ground barasingha (Rucervus duvaucelii branderi) lives in the sal forests and meadows of Kanha in Madhya Pradesh. It eats only grass (graminivorous) and, unlike its cousins, lives on firm ground. Kanha saved it from near extinction (about 66 animals in 1970). It is the state animal of Madhya Pradesh. Manas (b) holds the eastern swamp deer of Assam's wetlands. Mudumalai (c) has no barasingha. Tal Chhapar (d) in Rajasthan is famous for blackbuck.
Notice the other sub-species: the western swamp deer in the Terai (Dudhwa, Shuklaphanta) and the eastern one in Kaziranga. Kanha's mascot is "Bhoorsingh the Barasingha".
Answer as per the official UPSC answer key.
Read the passage
In India, the current focus on the right to privacy is based on some new realities of the digital age. A right is a substantive right only if it works in all situations, and for everyone. A right to free expression for an individual about her exploitation, for instance, is meaningless without actual availability of security that guarantees that private force cannot be used to thwart this right. The role of the State, therefore, is not just to abstain from preventing rightful free expression, but also to actively ensure that private parties are not able to block it.
On the basis of the above passage, the following assumptions have been made :
- 1. State should have some institutions to ensure its appropriate role in a digital society.
- 2. State should ensure that private parties do not violate the citizens’ right to privacy.
- 3. Digital economy is not compatible with the idea of not violating the citizens’ privacy.
Which of the above assumptions is/are valid?
Answer (a) & explanation
Assumptions 1 and 2 are valid (a). Step 1: the passage says the State must "actively ensure that private parties are not able to block" citizens' rights. So the State should stop private firms from violating privacy (2). Step 2: doing this needs proper institutions, such as regulators (1). Step 3: assumption 3 says a digital economy cannot respect privacy. That contradicts the passage, which wants the right to work "in all situations". So options (b), (c) and (d) fail.
Tip: privacy was declared a fundamental right in the Puttaswamy case (2017). The Digital Personal Data Protection Act, 2023 set up a Data Protection Board to enforce it. In CSAT, though, rely on the passage.
Answer as per the official UPSC answer key.
Consider the following sequence of numbers :
5 1 4 7 3 9 8 5 7 2 6 3 1 5 8 6 3 8 5 2 2 4 3 4 9 6
How many odd numbers are followed by the odd number in the above sequence?
Answer (b) & explanation
6 odd numbers are followed by an odd number (b). Step 1: go through the sequence and mark each pair of neighbours where both are odd. Step 2: the pairs are: 5 1, 7 3, 3 9, 5 7, 3 1 and 1 5. Step 3: that is 6 pairs. Each pair counts one odd number followed by an odd number. Options (a), (c) and (d) miscount.
Tip: in such counting questions, move through the list once, slowly, and tick each pair. Counting in a hurry is the main source of error. Odd digits are 1, 3, 5, 7 and 9.
7 3 9 gives two pairs (7 3 and 3 9). Count overlapping pairs separately.
Answer as per the official UPSC answer key.
Read the passage
In Part III of the Constitution, which assures people certain fundamental rights, Article 25 proclaims that “all persons are equally entitled to freedom of conscience and the right freely to profess, practise and propagate religion”. What people fail to notice is that this proclamation is prefixed with the words “subject to public order, morality, health and to the other provisions of this Part”, which set conditions precedent for the legal protection of religious practices of any community. The closing words of this prefatory rider in Article 25 virtually constitute a subordination clause placing other fundamental rights mentioned in Part III over and above the right to religious freedom. Among those other fundamental rights is the right to equality before law and equal protection of laws—assured at the outset and elaborated in later articles to mean, inter alia, that the State shall not deny equal protection of laws to any person or group of persons on the basis of religion alone.
What is the most logical inference from the above passage?
Answer (b) & explanation
The inference is that religious freedom under the Constitution is open to State intervention (b). Step 1: the passage says Article 25 is "subject to public order, morality, health" and to other fundamental rights. So the State can step in. That is (b). Step 2: options (a) and (d) say the State cannot interfere and that practices are immune to law. Both reverse the passage. Step 3: option (c) says religious freedom is not a fundamental right. That ignores Part III, where Articles 25–28 sit.
Tip: Article 25(2) also lets the State regulate secular activity linked to religion and open Hindu temples to all classes. Freedoms in India are rarely absolute.
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. The President of India can summon a session of the Parliament at such place as he/she thinks fit.
- 2. The Constitution of India provides for three sessions of the Parliament in a year, but it is not mandatory to conduct all three sessions.
- 3. There is no minimum number of days that the Parliament is required to meet in a year.
Which of the statements given above is/are correct?
Answer (c) & explanation
Statements 1 and 3 are correct (c). Statement 1 is right because Article 85 lets the President summon each House "at such time and place as he thinks fit". The only rule is that six months must not pass between two sessions. Statement 2 is wrong because the Constitution does not provide for three sessions. The Budget, Monsoon and Winter sessions are a convention. Statement 3 is right because there is no minimum number of sitting days.
The NCRWC suggested at least 120 days a year for the Lok Sabha, but sittings have fallen to about 55–70 days. Notice the new Parliament building, used since September 2023, where the first Bill passed was the Women's Reservation (106th Amendment) Act.
the "three sessions" are so familiar that students assume the Constitution lists them.
Answer as per the official UPSC answer key.
In the context of the Indian economy, non-financial debt includes which of the following ?
- 1. Housing loans owed by households
- 2. Amounts outstanding on credit cards
- 3. Treasury bills
Select the correct answer using the code given below :
Answer (d) & explanation
All three are non-financial debt (d). Non-financial debt is the debt owed by the non-financial sectors of an economy: households, non-financial companies and the government. Statement 1 is right because a housing loan is household debt. Statement 2 is right because credit card dues are also household debt. Statement 3 is right because Treasury Bills are short-term borrowing by the government. The only debt left out is that owed by banks and other financial firms, because counting it would double-count money already lent on.
Notice the related measures: the debt-to-GDP ratio of each sector, and the Bank for International Settlements (BIS), which publishes data on total credit to the non-financial sector. Treasury Bills have maturities of 91, 182 and 364 days.
"non-financial" sounds like it excludes loans and bills. It refers to who owes the debt, not what kind it is.
Answer as per the official UPSC answer key.
With reference to pulse production in India, consider the following statements :
- 1. Black gram can be cultivated as both kharif and rabi crop.
- 2. Green gram alone accounts for nearly half of pulse production.
- 3. In the last three decades, while the production of kharif pulses has increased, the production of rabi pulses has decreased.
Which of the statements given above is/are correct ?
Answer (a) & explanation
Only statement 1 is correct (a). Statement 1 is right: black gram (urad) is grown in both kharif and rabi, especially in the south and in rice fallows. Statement 2 is wrong: gram (chickpea), a rabi crop, gives nearly half of India's pulses; green gram (moong) has a much smaller share. Statement 3 is wrong: rabi pulse output, led by chickpea, has grown strongly over the past three decades, so the statement is reversed.
Notice that India is the world's largest producer, consumer and importer of pulses. Pulses are legumes that fix nitrogen. The Mission for Aatmanirbharta in Pulses (2025) aims to cut imports, focusing on tur, urad and masoor.
"gram" and "green gram" are different crops. Chickpea is the big one.
Answer as per the official UPSC answer key.
A simple mathematical operation in each number of the sequence 14, 18, 20, 24, 30, 32, ... results in a sequence with respect to prime numbers. Which one of the following is the next number in the sequence?
Answer (c) & explanation
The next number is 38 (c). Step 1: subtract 1 from each term: 14 − 1 = 13, 18 − 1 = 17, 20 − 1 = 19, 24 − 1 = 23, 30 − 1 = 29, 32 − 1 = 31. Step 2: these are prime numbers in order: 13, 17, 19, 23, 29, 31. Step 3: the next prime after 31 is 37. Add 1 back: 38. Option (a), 34, would need 33, not prime. Option (b), 36, needs 35, not prime. Option (d), 40, skips 37.
Tip: when a question hints at primes, try adding or subtracting 1 from each term. Know the primes up to 100 by heart.
Answer as per the official UPSC answer key.
Read the passage
Economic liberalization in India was shaped largely by the economic problems of the government than by the economic priorities of the people or by the long-term development objectives. Thus, there were limitations in conception and design which have been subsequently validated by experience. Jobless growth, persistent poverty and rising inequality have mounted as problems since economic liberalization began. And all these years later, four quiet crises confront the economy; agriculture, infrastructure, industrialization and education as constraints on the country’s future prospects. These problems must be resolved if economic growth has to be sustained and transformed into meaningful development.
Which of the following is/are the most rational and logical inference/inferences that can be made from the passage?
- 1. It is essential to rethink and redefine the economic role of the State in the quest for development.
- 2. India has not made effective implementation of its policies in social sectors nor made sufficient investments in them.
Select the correct answer using the code given below.
Answer (c) & explanation
Both inferences are valid (c). Step 1: the passage says reform was shaped by the government's problems, not the people's priorities. So the State's economic role needs rethinking (1). Step 2: it points to persistent poverty and a crisis in education. These show weak effort and spending in social sectors (2). Step 3: so options (a), (b) and (d) fail.
Tip: when a passage lists outcomes like poverty and poor schooling, it implies weak social-sector policy. "Rethink the role of the State" is a moderate claim that a critical passage can easily support.
Answer as per the official UPSC answer key.
A digit n > 3 is divisible by 3 but not divisible by 6. Which one of the following is divisible by 4?
Answer (d) & explanation
3n + 1 is divisible by 4 (d). Step 1: n is a single digit above 3, divisible by 3 but not by 6. Digits divisible by 3 above 3 are 6 and 9. 6 is divisible by 6, so n = 9. Step 2: test each option. 2n = 18; 3n = 27; 2n + 4 = 22; 3n + 1 = 28. Step 3: only 28 is divisible by 4. So the answer is (d). Options (a), (b) and (c) fail.
Tip: "digit" means 0 to 9. That small range lets you find n directly, then test options. Divisible by 3 but not 6 means an odd multiple of 3.
Answer as per the official UPSC answer key.
Indigo cultivation in India declined by the beginning of the 20th century because of
Answer (b) & explanation
New inventions made it unprofitable (b). In 1897, the German firm BASF began selling synthetic indigo, made in factories from chemicals. It was cheaper and more uniform than natural dye, and soon took over world markets. India's indigo exports collapsed by around 1914, with a brief revival during World War I. Option (a) is wrong because the Blue Mutiny (1859–60) drove planters out of Bengal, but they moved to Bihar, and the global decline came later. Option (c) is wrong because national leaders were not the cause; Gandhi's Champaran campaign (1917) came after the decline began. Option (d) is wrong because the government mostly supported the planters.
Notice Nil Darpan (1860) by Dinabandhu Mitra, the famous play on the planters' cruelty.
Peasant revolts did push the planters out of Bengal, but that does not explain an India-wide fall around 1900.
Answer as per the official UPSC answer key.
In which one of the following groups are all the four countries members of G20 ?
Answer (a) & explanation
Argentina, Mexico, South Africa and Turkey are all G20 members (a). The G20 has 19 countries plus the European Union, and the African Union joined in 2023 at India's New Delhi summit. The 19 are Argentina, Australia, Brazil, Canada, China, France, Germany, India, Indonesia, Italy, Japan, Mexico, Russia, Saudi Arabia, South Africa, South Korea, Turkey, the UK and the USA. Option (b) fails because of Malaysia and New Zealand. Option (c) fails because of Iran and Vietnam. Option (d) fails because of Singapore.
Notice that the G20 began in 1999 as a meeting of finance ministers after the Asian financial crisis and became a leaders' summit in 2008. It has no permanent secretariat; the troika of past, present and next presidencies guides it.
each wrong option has three members and one outsider. Find the outsider: Malaysia, Iran, Singapore.
Answer as per the official UPSC answer key.
With reference to the history of India, consider the following pairs :
| Famous Place | Present State
| 1. Bhilsa | Madhya Pradesh
| 2. Dwarasamudra | Maharashtra
| 3. Girinagar | Gujarat
| 4. Sthanesvara | Uttar Pradesh
Which of the pairs given above are correctly matched ?
Answer (a) & explanation
Pairs 1 and 3 are correct (a). Pair 1 is right: Bhilsa is the old name of Vidisha in Madhya Pradesh, near Sanchi, where the Heliodorus pillar stands. Pair 2 is wrong: Dwarasamudra (Halebidu) was the Hoysala capital in Karnataka, not Maharashtra. Pair 3 is right: Girinagar is Girnar near Junagadh, Gujarat, the site of Ashoka's edicts and Rudradaman's inscription. Pair 4 is wrong: Sthanesvara (Thanesar), the first capital of Harsha's Pushyabhuti family, is in Haryana, not Uttar Pradesh.
Notice that Sudarshana lake at Girnar was built under the Mauryas and repaired by Rudradaman and later by Skandagupta. Harsha later moved his capital to Kannauj.
Answer as per the official UPSC answer key.
Read the passage
Our urban bodies cannot possibly ensure sustainable delivery of water in our cities unless financing mechanisms are put in place. Water delivery requires heavy investment in collecting it from a natural source, treating it to make it potable, and laying a distribution network of pipes for delivery to the users. It also requires investments in sewerage infrastructure and sewage treatment plants so that the sewers can carry the wastewater to these plants to ensure that no untreated sewage is discharged back into natural water bodies. If our cities were rich enough to meet the entire cost, water could be delivered free. They are not.
What is the most logical and crucial message conveyed by the passage?
Answer (a) & explanation
The message is that urban local bodies must recover costs through user charges (a). Step 1: the passage says water delivery needs heavy investment, and cities cannot meet "the entire cost" themselves. So water cannot be free; users must pay. That is (a). Step 2: option (b), that local bodies are inefficient, is not raised. Option (d), capping city population, is also not raised. Step 3: option (c) says the shortage cannot be solved. That is defeatist; the passage offers a way, user charges.
Tip: when a passage stresses cost, the message usually concerns who pays. Choose the option that offers the passage's own solution, not an extreme one.
Answer as per the official UPSC answer key.
What is the remainder when 51 × 27 × 35 × 62 × 75 is divided by 100?
Answer (a) & explanation
The remainder is 50 (a). Step 1: the remainder on dividing by 100 is just the last two digits. So keep only the last two digits at each step. Step 2: 35 × 62 = 2170 → 70. 70 × 75 = 5250 → 50. 50 × 27 = 1350 → 50. 50 × 51 = 2550 → 50. Step 3: the remainder is 50. Option (b), 25, and option (c), 5, come from multiplying only the 5-ending numbers. Option (d) fails.
Tip: an even number times a multiple of 25 gives a multiple of 50. Here 62 is even and 75 is a multiple of 25, and the other factors are odd, so the product ends in 50.
Answer as per the official UPSC answer key.
In India, Legal Services Authorities provide free legal services to which of the following type of citizens?
- 1. Person with an annual income of less than ₹ 1,00,000
- 2. Transgender with an annual income of less than ₹ 2,00,000
- 3. Member of Other Backward Classes (OBC) with an annual income of less than ₹ 3,00,000
- 4. All Senior Citizens
Select the correct answer using the code given below :
Answer (a) & explanation
Statements 1 and 2 are correct (a). Section 12 of the Legal Services Authorities Act, 1987 lists who gets free legal aid. They include members of SCs and STs, women and children, persons with disabilities, victims of trafficking or disasters, industrial workmen, people in custody, and those whose income is below a limit set by rules. When this question was set, the rules covered persons with income under ₹1 lakh (1), and some states covered transgender persons with income under ₹2 lakh (2). Statement 3 is wrong because there is no OBC category. Statement 4 is wrong because not all senior citizens are covered, only those meeting income limits in some states.
This puts Article 39A into effect. Notice NALSA, the Lok Adalats, and the Legal Aid Defense Counsel system (2022).
"All" senior citizens. Age alone does not qualify anyone for free legal aid under the Act.
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. Genetic changes can be introduced in the cells that produce eggs or sperms of a prospective parent.
- 2. A person’s genome can be edited before birth at the early embryonic stage.
- 3. Human induced pluripotent stem cells can be injected into the embryo of a pig.
Which of the statements given above is/are correct ?
Answer (d) & explanation
All three statements are correct (d). Gene-editing tools such as CRISPR-Cas9 can change the DNA of germline cells, the cells that make eggs or sperm (1). Such changes would pass to future generations. A person's genome can be edited at the early embryo stage (2), as in the 2018 case of the Chinese scientist He Jiankui, who made the first gene-edited babies and was jailed. Human induced pluripotent stem (iPS) cells, made by reprogramming adult cells, have been injected into pig embryos to make human–pig chimeras (3), for research into growing human organs.
These are all technically possible but ethically debated. Notice the newer step: pig kidneys and hearts, genetically edited, were transplanted into living humans in the USA (2022–25).
Answer as per the official UPSC answer key.
Steel slag can be the material for which of the following ?
- 1. Construction of base road
- 2. Improvement of agricultural soil
- 3. Production of cement
Select the correct answer using the code given below :
Answer (d) & explanation
Steel slag can be used for all three (d). Steel slag is the stony waste left over when lime is used to remove impurities from molten iron in steel-making. Use 1 is right: crushed slag is hard and strong, so it is used in road base and sub-base layers; India's first steel slag road was built in Surat (2022). Use 2 is right: slag is rich in lime (calcium) and some silicates, so it can correct acidic soils. Use 3 is right: granulated blast furnace slag is ground into Portland Slag Cement, cutting the need for clinker.
Notice the idea of a circular economy: turning industrial waste into resources. Fly ash from power plants is reused the same way, in bricks and cement.
Answer as per the official UPSC answer key.
Read the passage
One of the biggest ironies around water is that it comes from rivers and other wetlands. Yet it is seen as divorced from them. While water is used as a resource, public policy does not always grasp that it is a part of the natural ecosystem. Efforts at engineering water systems are thus efforts at augmenting water supply rather than strengthening the capacities of ecological systems.
Which one of the following is the most logical and rational inference that can be made from the above passage?
Answer (c) & explanation
The inference is that wetlands must be seen as more than just open sources of water (c). Step 1: the passage says policy treats water as a resource "divorced" from wetlands. It ignores the wetland as a living ecosystem. So wetlands should be valued for more than water. That is (c). Step 2: option (b) asks to expand engineered water systems. That repeats the very approach the passage criticises. Step 3: option (a), the Ramsar Convention, is outside knowledge not in the passage. Option (d), charging for water, is not discussed.
Tip: avoid options that rely on facts the passage never gives, even if true. India has 90+ Ramsar sites, but that does not make (a) the inference here.
Answer as per the official UPSC answer key.
A is 16th from the left end in a row of boys and V is 18th from the right end. G is 11th from A towards the right and 3rd from V towards the right end. How many boys are there in the row?
Answer (b) & explanation
There are 41 boys in the row (b). Step 1: A is 16th from the left. G is 11 places to A's right, so G is 16 + 11 = 27th from the left. Step 2: G is 3rd from V towards the right, so V is 3 places to G's left: 24th from the left. Step 3: V is also 18th from the right. Total = 24 + 18 − 1 = 41. We subtract 1 because V is counted twice. Option (c), 42, forgets to subtract 1. Options (a) and (d) fail.
Tip: total in a row = position from left + position from right − 1. Fix one person's position from both ends to use this formula.
Answer as per the official UPSC answer key.