UPSC Prelims PYQs with explanations
Real questions from official papers, mapped to syllabus topics. Attempt each one; the answer and the reason appear instantly.
Read the passage
Spanish ships in the late 16th century first brought the potato tuber from South America to Europe whereby in the early 19th century, it had become a reliable backup to cereal crops, particularly in the cold, rain-soaked soils of Ireland. The Irish were soon almost wholly dependent on the potato as their staple food. And they were planting primarily one prodigious variety, the ‘Lumper’ potato, whose genetic frailty would be cruelly exposed by the fungus ‘Phytophthora infestans’. In 1845, spores of the deadly fungus began spreading across the country, destroying nearly all the Lumpers in its path. The resulting famine killed or displaced millions.
Which one of the following statements best reflects the critical message of the passage?
Answer (d) & explanation
The critical message is that relying on one uniform food source is unwise (d). Step 1: the passage says the Irish depended almost wholly on one potato variety, and one fungus wiped it out, causing famine. So depending on a single, uniform food is risky. That is (d). Step 2: option (a), suitable soil and climate, misses the point; the potato grew well in Ireland. Step 3: option (c), some fungal infections cannot be stopped, is too general. Option (b), tubers cannot replace cereals, is not the message.
Tip: this is the Irish Potato Famine of the 1840s. It is the classic warning against monoculture and a reason to keep crop diversity.
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. The minimum number of points of intersection of a square and a circle is 2.
- 2. The maximum number of points of intersection of a square and a circle is 8.
Which of the above statements is/are correct?
Answer (b) & explanation
Only statement 2 is correct (b). Step 1: statement 1 says the minimum number of meeting points is 2. But a circle can lie completely away from the square, or fully inside without touching it. Then there are 0 points. So 1 is false. Step 2: statement 2: a circle can cut each of the 4 sides twice, when it is a bit larger than the inscribed circle. That gives 8 points. So 2 is true. Step 3: so options (a), (c) and (d) fail.
Tip: a straight line can meet a circle at most twice. Multiply by the number of sides to get the maximum for any polygon: a triangle gives 6, a square 8.
Answer as per the official UPSC answer key.
With reference to the history of India, the terms “kulyavapa” and “dronavapa” denote
Answer (a) & explanation
They denote measurements of land (a). Gupta-period land grants from Bengal, such as those at Paharpur and Damodarpur, measure land in kulyavapa and dronavapa. The names come from the amount of seed needed to sow the plot: a kulya or a drona measure. A kulyavapa was larger, about eight dronavapas. These grants show that land was being bought and sold, and given to Brahmins and Buddhist monasteries. They were not coins (b), urban land classes (c) or rituals (d).
Notice other Gupta land terms: nivartana in central and western India, and padavarta. The Gupta land grants are used by historians to argue that Indian feudalism grew in this period, with agraharas and rights over villagers passing to grantees.
Answer as per the official UPSC answer key.
In India, which of the following can be considered as public investment in agriculture ?
- 1. Fixing Minimum Support Price for agricultural produce of all crops
- 2. Computerization of Primary Agricultural Credit Societies
- 3. Social Capital development
- 4. Free electricity supply to farmers
- 5. Waiver of agricultural loans by the banking system
- 6. Setting up of cold storage facilities by the governments
Select the correct answer using the code given below :
Answer (c) & explanation
Items 2, 3 and 6 are public investment (c). Investment creates lasting assets that raise future output. Item 2 is right because computerising PACS builds systems that last. Item 3 is right because social capital, such as farmer groups and trained cooperatives, is a lasting asset. Item 6 is right because cold storage cuts post-harvest losses for years. Item 1 is wrong: MSP is a price policy, not an asset. Items 4 and 5 are wrong: free electricity and loan waivers are subsidies or transfers; they support current income but build nothing.
Notice the common critique that heavy farm subsidies crowd out public investment in irrigation, research and roads. Public investment is part of gross capital formation in agriculture.
loan waivers and free power cost the government a lot. Big spending is not the same as investment.
Answer as per the official UPSC answer key.
With reference to Ocean Mean Temperature (OMT), which of the following statements is/are correct ?
- 1. OMT is measured up to a depth of 26°C isotherm which is 129 meters in the south-western Indian Ocean during January – March.
- 2. OMT collected during January – March can be used in assessing whether the amount of rainfall in monsoon will be less or more than a certain long-term mean.
Select the correct answer using the code given below :
Answer (b) & explanation
Only statement 2 is correct (b). Ocean Mean Temperature is the average sea temperature from the surface down to the depth of the 26 °C isotherm. Statement 1 is wrong per the key: in the south-western Indian Ocean in January–March, the 26 °C isotherm does not lie at the 129 metres the statement claims. Statement 2 is right: studies found that OMT in January–March predicts whether the monsoon will be above or below the long-term mean better than sea surface temperature does, because it captures the ocean's stored heat.
Notice the other monsoon drivers: El Niño, the Indian Ocean Dipole and the MJO. The IMD issues its first monsoon forecast in April, against a long-period average of about 87 cm.
Answer as per the official UPSC answer key.
If in a particular year 12th January is a Sunday, then which one of the following is correct?
Answer (c) & explanation
12th July is a Sunday if the year is a leap year (c). Step 1: days from 12 January to 12 July = 31 (Jan) + 28 (Feb) + 31 (Mar) + 30 (Apr) + 31 (May) + 30 (Jun) = 181 days. In a leap year, February has 29, so it is 182. Step 2: 182 = 7 × 26, an exact number of weeks. So in a leap year, 12 July falls on the same day, Sunday. Step 3: option (d) says the opposite, so it fails. Options (a) and (b) about 15 July do not work: 15 July would be Wednesday (leap) or Tuesday (non-leap).
Tip: count days between dates and divide by 7. The remainder tells how many days the weekday moves forward.
Answer as per the official UPSC answer key.
Consider the following data :
| Year | Birthrate | Death rate |
|---|---|---|
| 1911–1921 | 48·1 | 35·5 |
| 1921–1931 | 46·4 | 36·3 |
| 1931–1941 | 45·2 | 31·2 |
| 1941–1951 | 39·9 | 27·4 |
| 1951–1961 | 41·7 | 22·8 |
| 1961–1971 | 41·1 | 18·9 |
| 1971–1981 | 37·1 | 14·8 |
For which period was the natural growth rate maximum?
Answer (d) & explanation
Natural growth rate was highest in 1971–1981 (d). Step 1: natural growth = birth rate − death rate. Step 2: from the table: 1911–21: 12·6; 1941–51: 12·5; 1961–71: 22·2; 1971–81: 22·3. Step 3: the biggest is 22·3, in 1971–1981. Option (c), 1961–71, is very close but slightly lower. Options (a) and (b) are much lower.
Tip: when two values are close, calculate carefully; UPSC often places a near-miss option. Historically, India's growth peaked around 1961–81 as death rates fell faster than birth rates.
1961–71 (22·2) is very close; subtract carefully.
Answer as per the official UPSC answer key.
In India, separation of judiciary from the executive is enjoined by
Answer (b) & explanation
A Directive Principle requires it (b). Article 50, in Part IV, directs the State to take steps to separate the judiciary from the executive in the public services of the State. The aim is that the same officers should not both run the administration and judge cases. The Code of Criminal Procedure, 1973 put this into effect by creating separate judicial magistrates, while executive magistrates handle law and order. The Preamble (a) does not mention it. The Seventh Schedule (c) divides subjects between the Centre and states. It is not merely a convention (d).
Notice that judicial independence and the separation of powers are part of the basic structure. The CrPC was replaced by the Bharatiya Nagarik Suraksha Sanhita in July 2024, which keeps this separation.
Answer as per the official UPSC answer key.
With reference to “Blockchain Technology”, consider the following statements :
- 1. It is a public ledger that everyone can inspect, but which no single user controls.
- 2. The structure and design of blockchain is such that all the data in it are about cryptocurrency only.
- 3. Applications that depend on basic features of blockchain can be developed without anybody’s permission.
Which of the statements given above is/are correct ?
Answer (d) & explanation
Statements 1 and 3 are correct (d). A blockchain is a distributed ledger: a chain of linked, time-stamped records copied across many computers. Statement 1 is right because a public blockchain can be inspected by anyone, and no single user controls it; changes need agreement across the network. Statement 2 is wrong because it can record any data, such as land titles, supply chains, medical records, voting or certificates, not just cryptocurrency. Statement 3 is right because open, permissionless chains let anyone build applications, such as smart contracts, without asking permission.
Notice India's uses: land records pilots, Vishvasya, the national blockchain framework (2024), and the RBI's e-rupee (CBDC). India taxes crypto gains at 30% but has not banned crypto.
Answer as per the official UPSC answer key.
With reference to Indian elephants, consider the following statements :
- 1. The leader of an elephant group is a female.
- 2. The maximum gestation period can be 22 months.
- 3. An elephant can normally go on calving till the age of 40 years only.
- 4. Among the States in India, the highest elephant population is in Kerala.
Which of the statements given above is/are correct ?
Answer (a) & explanation
Statements 1 and 2 are correct (a). Statement 1 is right: an elephant herd is led by the oldest female, the matriarch, who remembers routes and water sources. Adult males usually live alone or in small groups. Statement 2 is right: pregnancy lasts about 22 months, the longest of any mammal. Statement 3 is wrong: female elephants can calve into their fifties and beyond, not just till 40. Statement 4 is wrong: Karnataka has the largest elephant population in India, followed by Assam and Kerala.
Notice that the Asian elephant is Endangered on the IUCN Red List and is in Schedule I of the Wildlife Protection Act. Project Elephant began in 1992. World Elephant Day is 12 August.
"40 years only": the word "only" makes 3 easy to reject.
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Answer as per the official UPSC answer key.
Which one of the following categories of Fundamental Rights incorporates protection against untouchability as a form of discrimination?
Answer (d) & explanation
Protection against untouchability falls under the Right to Equality (d). Article 17 abolishes untouchability and forbids its practice in any form. Enforcing any disability arising from it is a punishable offence. It sits in the Right to Equality group, Articles 14 to 18, along with equality before law (14), no discrimination (15), equal opportunity in jobs (16) and abolition of titles (18). The Right against Exploitation (a) covers trafficking, forced labour and child labour (Articles 23–24). The Right to Freedom (b) covers Articles 19–22. Constitutional Remedies (c) is Article 32.
Article 17 is one of the few rights enforceable even against private persons. Notice the laws under it: the Protection of Civil Rights Act, 1955 and the SC/ST (Prevention of Atrocities) Act, 1989.
untouchability "feels" like exploitation (Articles 23-24), but it is placed with equality.
Answer as per the official UPSC answer key.
A man walks down the backside of his house straight 25 metres, then turns to the right and walks 50 metres again; then he turns towards left and again walks 25 metres. If his house faces to the East, what is his direction from the starting point?
Answer (d) & explanation
He is North-West of his starting point (d). Step 1: the house faces East, so its back side faces West. He walks 25 m West. Step 2: facing West, a right turn points him North. He walks 50 m North. Facing North, a left turn points him West. He walks 25 m West. Step 3: net movement: 25 + 25 = 50 m West and 50 m North. Equal amounts of West and North give North-West. Options (a), (b) and (c) fail.
Tip: draw a quick sketch with N at the top. Remember: facing West, right is North and left is South. Equal moves in two directions give the in-between direction.
Answer as per the official UPSC answer key.
Read the passage
India has tremendous potential for solar energy. We all realize that we have to stop burning fossil fuels to meet our energy needs. But certain renewable resources are still going through their cost curves and learning curves to get the required amount of output. The Indian Government has strongly committed to its targets of reducing emissions by 33 per cent by 2030, and towards this it has initiated a strong push towards a gas-based economy and has also invested heavily in renewable energy. However, business houses are wary of investing too heavily in renewable energy at a time when the technology is not yet ready.
With reference to the above passage, the following assumptions have been made :
- 1. Governments often provide inefficient and costly subsidies for technologies that may not be ready in the near future.
- 2. India’s commitment of reducing emissions by 33% by 2030 shall be on the basis of gas-based economy.
Which of the above assumptions is/are valid?
Answer (a) & explanation
Only assumption 1 is valid (a). Step 1: UPSC's key reads the passage's point about heavy state support for a technology that is "not yet ready" as costly and inefficient subsidy (1). Step 2: assumption 2 says the 33% emissions target will rest on a gas-based economy. But the passage says the target depends on gas and renewables, not gas alone. So 2 fails. Step 3: so options (b), (c) and (d) fail.
Tip: watch for an option that keeps one part of a pair and drops the other. "Gas and renewables" does not mean "gas-based". India later updated its Paris goal to 45% lower emissions intensity by 2030 (from 2005 levels).
Answer as per the official UPSC answer key.
"Gold Tranche" (Reserve Tranche) refers to
Answer (d) & explanation
The Gold Tranche is an IMF credit system for members (d). Each IMF member has a quota, which sets its contribution, its voting power and how much it can borrow. Part of the quota, originally 25%, is paid in gold or hard currency; this is the reserve tranche, once called the gold tranche. A member can draw it at any time, with no conditions and no interest, because it is really its own money. It is not a World Bank loan system (a), a central bank operation (b), or a WTO credit (c).
Notice that the reserve tranche counts as part of India's forex reserves, with gold, foreign currency assets and SDRs. India's IMF quota share is about 2.75%, and the 16th review aims at a quota increase.
the word "gold" points to a central bank vault. The tranche is a slice of the member's IMF quota.
Answer as per the official UPSC answer key.
With reference to Foreign Direct Investment in India, which one of the following is considered its major characteristic ?
Answer (b) & explanation
FDI is largely a non-debt creating flow (b). Foreign Direct Investment buys ownership (equity) in an Indian business, usually with a say in management. There is no fixed interest to pay and no loan to return, so it adds no external debt and is a stable source of capital. Option (a) is wrong because FDI can go into listed or unlisted companies; in a listed company, a holding of 10% or more counts as FDI, below that as portfolio investment. Option (c) describes External Commercial Borrowings, which need debt-servicing. Option (d) describes FPI in government securities, which is portfolio debt.
Notice the two FDI routes: automatic (no prior approval) and government approval. Singapore and Mauritius have long been the top sources of FDI into India.
option (a) says "essentially in a listed company". FDI often goes into unlisted companies too.
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Answer as per the official UPSC answer key.
What is/are the advantage/advantages of zero tillage in agriculture ?
- 1. Sowing of wheat is possible without burning the residue of previous crop.
- 2. Without the need for nursery of rice saplings, direct planting of paddy seeds in the wet soil is possible.
- 3. Carbon sequestration in the soil is possible.
Select the correct answer using the code given below :
Answer (d) & explanation
All three are advantages of zero tillage (d). In zero tillage, the field is not ploughed before sowing. Statement 1 is right: machines like the Happy Seeder sow wheat straight into rice stubble, so farmers need not burn the residue. Statement 2 is right: Direct Seeded Rice drills paddy seed into the soil, with no nursery or transplanting, saving water and labour. Statement 3 is right: undisturbed soil keeps more organic matter, so carbon stays locked in the soil instead of escaping as CO₂.
Notice the wider package, called conservation agriculture: minimal tillage, crop residue cover and crop rotation. Zero tillage also saves diesel and lets wheat be sown on time after the rice harvest.
Answer as per the official UPSC answer key.
How many five-digit prime numbers can be obtained by using all the digits 1, 2, 3, 4 and 5 without repetition of digits?
Answer (a) & explanation
No such prime exists, so the answer is zero (a). Step 1: any number made from all of 1, 2, 3, 4 and 5 has a digit sum of 1 + 2 + 3 + 4 + 5 = 15. Step 2: 15 is divisible by 3, so every such number is divisible by 3. Step 3: a number divisible by 3 (and bigger than 3) is not prime. So there are zero such primes. Options (b), (c) and (d) fail.
Tip: before counting arrangements, check the digit sum. If it is divisible by 3, no arrangement can be prime. This trick saves you from listing 120 numbers.
Answer as per the official UPSC answer key.
Read the passage
India is at once among the fastest growing global economies and home to the largest number of malnourished children in the world. There are regions where malnutrition is not the exception but the norm. And across the country, malnutrition is the cause of death for roughly half the 1·3 million children who die before their fifth birthday each year. Even those children who survive suffer permanently from the damage that has already been done to their bodies and minds from not getting enough of the right foods and nutrients. Around 44 million children under 5 are stunted. That makes it harder for them to learn in school and subsequently earn a living as adults. Their lifetime earnings potential is almost a quarter less than that of their healthy peers.
With reference to the above passage, which of the following is/are the most rational and practical implication/implications?
- 1. India’s Public Distribution System should be monitored by the Union Government.
- 2. Girls should be encouraged to delay marriage and first pregnancy.
- 3. Mothers should be encouraged to breastfeed their children immediately after birth.
- 4. The supply of safe drinking water and proper sanitation facilities to all should be ensured.
- 5. Authorities should ensure the vaccination as prescribed.
Select the correct answer using the code given below.
Answer (b) & explanation
Implications 2, 3, 4 and 5 are rational and practical (b). Step 1: the passage says most damage from malnutrition happens before age five. So steps should target mothers and young children. Step 2: delaying marriage and first pregnancy (2), early breastfeeding (3), safe water and sanitation (4) and proper vaccination (5) all protect young children. Step 3: statement 1, Union monitoring of the PDS, is an administrative change the passage does not imply. So options (a), (c) and (d) fail.
Tip: India's legal minimum marriage age for women is 18. Breastfeeding within the first hour of birth is a key WHO advice point. Link each option to the passage's focus: early childhood.
Answer as per the official UPSC answer key.
A man takes half time in rowing a certain distance downstream than upstream. What is the ratio of the speed in still water to the speed of current?
Answer (d) & explanation
The ratio of speed in still water to current is 3 : 1 (d). Step 1: the same distance takes half the time downstream, so the downstream speed is double the upstream speed. Step 2: let the boat's speed be b and the current c. Downstream = b + c; upstream = b − c. So b + c = 2(b − c). Step 3: this gives b + c = 2b − 2c, so b = 3c. Ratio = 3 : 1. Option (b), 2 : 1, is the ratio of the speeds, not of boat to current. Options (a) and (c) fail.
Tip: downstream adds the current, upstream subtracts it. Half the time means double the speed for the same distance.
Answer as per the official UPSC answer key.
Who among the following rulers advised his subjects through this inscription ?
“Whosoever praises his religious sect or blames other sects out of excessive devotion to his own sect, with the view of glorifying his own sect, he rather injures his own sect very severely.”
Answer (a) & explanation
Ashoka issued this advice (a). The lines come from Ashoka's Major Rock Edict XII, which is about respect between religious sects. It asks people to control their speech (vachaguti), not to praise their own sect or criticise others without reason, and to listen to the teachings of other sects. Ashoka said that whoever glorifies his own sect by running down others actually harms it. This tolerance was a key part of his dhamma. Samudragupta (b) is known from the Allahabad Pillar praise by Harisena. Harshavardhana (c) held assemblies at Kannauj and Prayag. Krishnadeva Raya (d) wrote Amuktamalyada.
Notice that Ashoka's edicts were mostly in Prakrit and Brahmi, with Kharosthi, Greek and Aramaic in the north-west.
Answer as per the official UPSC answer key.