CSAT (Paper II): previous-year questions
1280 real UPSC Prelims questions (2011–2026) with the official answer and a clear explanation. 400 of them came in the last five papers.
How often UPSC asks this
Questions per year, counted from the official papers.
Subtopics
Arrangements, ranking, ordering and puzzles
142 questions
Clocks and calendars
5 questions
Coding-decoding, series, patterns, cubes, dice and visual reasoning
110 questions
Communication, interpersonal skills and decision-making
10 questions
Counting, permutations, combinations and probability
1 questions
Directions, blood relations and Venn diagrams
60 questions
General English: grammar, vocabulary and comprehension
20 questions
General Hindi: grammar, vocabulary, dialects and comprehension
25 questions
Geometry and mensuration
26 questions
Number system and basic algebra (divisibility, HCF/LCM, remainders, digits, equations)
196 questions
Percentages, profit and loss, discount, simple and compound interest
47 questions
Ratio, proportion, averages, mixtures and alligation
47 questions
Syllogisms, statements and conclusions, assumptions and arguments
89 questions
Time and work; pipes and cisterns
2 questions
Time, speed and distance; trains, boats and streams; races
48 questions
Attempt the questions
Newest papers first. Tap an option; the answer and the reason appear instantly.
In the sum
⊗ + 1⊗ + 5⊗ + ⊗⊗ + ⊗1 = 1⊗⊗
for which digit does the symbol ⊗ stand?
Answer (b) & explanation
The symbol stands for 3 (b). Step 1: test the options. Put ⊗ = 3. Step 2: left side: 3 + 13 + 53 + 33 + 31 = 133. Step 3: right side: 1⊗⊗ = 133. Both sides match, so ⊗ = 3. Check another: ⊗ = 2 gives 2 + 12 + 52 + 22 + 21 = 109, but 1⊗⊗ = 122. No match. Options (a), (c) and (d) fail.
Tip: when an equation has one unknown digit and four options, plugging in is quickest. Algebra also works: the left side is 24⊗ + 61 and the right side is 100 + 11⊗, so 13⊗ = 39 and ⊗ = 3.
Trying the four options is quicker than any algebra here.
Answer as per the official UPSC answer key.
Read the passage
The pulse variety ‘Pusa Arhar 16’ has the potential to be grown in the paddy-growing regions of Punjab, Haryana and Uttar Pradesh and eventually in all of India. Its yield (about 2000 kg/hectare) will be significantly greater than those of the existing varieties and because its size will be uniform, it will be amenable to mechanical harvesting, an attractive feature for farmers in northern India who currently use this technology for paddy. Most important, Arhar straw, unlike paddy straw, is green and can be ploughed back into the soil. In paddy straw, the problem is the high silica content, which does not allow for easy decomposition. In the case of Arhar, the farmer, even after combine harvesting, just needs to run a rotovator to cut the leftover straw into pieces, which can be ploughed back and will decompose very fast. All this is difficult with leftover paddy stalks that cannot be easily salvaged or ploughed back. Farmers, therefore, choose the easiest option of simply burning it.
Which of the following are the most rational inferences that can be made from the passage?
- 1. Farmers’ income will be higher with pulse cultivation than with paddy cultivation.
- 2. Pulse cultivation causes less pollution as compared to paddy cultivation.
- 3. Pulse straw can be used to improve soil quality.
- 4. In the context of northern Indian agriculture, paddy straw has no usefulness.
- 5. Mechanized agriculture is the main cause for stubble burning.
Select the correct answer using the code given below.
Answer (c) & explanation
Inferences 2 and 3 only (c). Step 1: the passage says arhar (pulse) straw is ploughed back into the soil and decomposes. So pulse straw improves soil (3). Step 2: paddy straw is burnt, causing smoke. So pulses cause less pollution than paddy (2). Step 3: statement 1, farmers' income, is not compared. Statement 4, paddy straw has no use, is too absolute. Statement 5 fails: the passage says paddy straw is burnt because of its high silica, not because of mechanisation. So options (a), (b) and (d) fail.
Tip: stubble burning in Punjab and Haryana adds to Delhi's winter smog. In CSAT, though, use the passage's stated reason, here silica.
Answer as per the official UPSC answer key.
How many pairs of natural numbers are there such that the difference of whose squares is 63?
Answer (a) & explanation
There are 3 such pairs (a). Step 1: x² − y² = (x − y)(x + y) = 63. Both factors must be odd, because 63 is odd, and x + y is the larger factor. Step 2: factor pairs of 63: 1 × 63, 3 × 21, 7 × 9. Step 3: solve each. 1 and 63: x = 32, y = 31. 3 and 21: x = 12, y = 9. 7 and 9: x = 8, y = 1. That is 3 pairs. Check: 64 − 1 = 63. Options (b), (c) and (d) miscount.
Tip: for x² − y² = N, count the factor pairs of N with the same parity (both odd or both even). Each gives one solution.
Answer as per the official UPSC answer key.
Read the passage
Many opportunities to harness the highly skewed, seasonal and spatial distribution of monsoon flows, which occur in a four-month period from June to September annually, have been lost. Since these few months account for most of the rainfall and consequent freshwater availability, the need for holding rainwater in reservoirs, for subsequently releasing it for use over the year, is a necessity nobody can afford to overlook. Climate change will continue to affect weather conditions and create water shortages and excesses. While millions suffer from droughts and floods, waters in the country’s many rivers flow unutilized, and are discharged into the sea every year.
With reference to the above passage, which of the following could be the most rational and practical implications for India?
- 1. Inter-linking of rivers should be undertaken.
- 2. A network of dams and canals should be built across the country for proper distribution of water.
- 3. Farmers should be provided easy loans for digging borewells.
- 4. Usage of water for agriculture should be regulated by law.
- 5. Distribution of river water among regions should be regulated by the Union Government.
Select the correct answer using the code given below.
Answer (a) & explanation
Implications 1 and 2 are rational and practical (a). Step 1: the passage says monsoon water should be stored in reservoirs and moved from flood-hit to drought-hit areas, instead of flowing into the sea. This points to inter-linking rivers (1) and a network of dams and canals (2). Step 2: statement 3, loans for borewells, would pull more groundwater; the passage does not suggest it. Step 3: statement 4, a law on farm water use, and statement 5, Union control of river sharing, are not discussed. So options (b), (c) and (d) fail.
Tip: India's Ken–Betwa link, whose foundation stone was laid in December 2024, is the first project under the national river-linking plan.
Answer as per the official UPSC answer key.
What is the least four-digit number when divided by 3, 4, 5 and 6 leaves a remainder 2 in each case?
Answer (b) & explanation
The least such number is 1022 (b). Step 1: a number leaving remainder 2 when divided by 3, 4, 5 and 6 has the form LCM × k + 2. LCM(3, 4, 5, 6) = 60. Step 2: the smallest four-digit multiple of 60: 60 × 17 = 1020. Step 3: add 2: 1022. Option (a), 1012, is 60 × 16·8 + 2, not valid. Option (c), 1122 = 60 × 18·67 + 2, fails. Option (d) also fails.
Tip: same remainder for all divisors → number = LCM × k + remainder. Find the LCM, then the first suitable multiple.
Answer as per the official UPSC answer key.
Read the passage
In India, over the last decade or so, labour has been departing agriculture, but is only going to construction and unregistered manufacturing which are not markedly better jobs. Services, where labour tends to be most productive, are not generating the additional jobs the country needs. India will need 24 million or so jobs over the next decade. The new sector, e-commerce, can at best close only half the jobs gap. Only those sectors that drive domestic demand such as health and education can comfortably fill the other half.
Which one of the following is best implied in the passage?
Answer (d) & explanation
The passage best implies that more social-sector spending is vital for large-scale job creation (d). Step 1: it says only health and education "can comfortably fill the other half" of the jobs gap. So spending on these sectors is key to creating jobs. That is (d). Step 2: option (c) says services are reducing unemployment. The passage says they are not generating enough jobs, so (c) is false. Step 3: option (a), stopping rural-urban migration, and option (b), better working conditions in construction, are not the passage's point.
Tip: look for the line that offers a solution; it usually holds the implication. Health and education are labour-intensive, so they create many jobs per rupee spent.
Answer as per the official UPSC answer key.
Two Statements are given followed by two Conclusions :
Statements : All cats are dogs. All cats are black.
Conclusion-I : All dogs are black.
Conclusion-II : Some dogs are not black.
Which of the above Conclusions logically follows/follow from the two given Statements, disregarding commonly known facts?
Answer (c) & explanation
Neither conclusion follows (c). Step 1: "All cats are dogs" puts the cats inside the dogs group. "All cats are black" says the cats are black. Step 2: so we know the cat part of the dogs is black. The other dogs may or may not be black. Step 3: so "all dogs are black" (I) is not certain, and "some dogs are not black" (II) is not certain either. Neither follows. Options (a), (b) and (d) fail.
Tip: draw circles: a small "cats" circle inside "dogs", also inside "black". The rest of "dogs" is unknown. When I and II are opposites, check if they form an either-or pair; here they do not, because "all dogs are black" is only possible, not certain.
I and II are opposites, so one of them must be true. But neither follows by itself, and no option says 'either I or II'.
Answer as per the official UPSC answer key.
Read the passage
Many people understand the connection between solid waste management and health in terms of the consequences of unattended heaps of dry garbage which become home for flies and other vermin. However, there is another aspect that is not well-understood, that is, what happens when unscientific solid waste management combines with poor drainage and dumping of untreated sewage into drains which are meant to carry storm water during rains. The result is choked drains which are full of stagnant water breeding mosquitoes, resulting in the spread of water-borne diseases.
In the context of India, which one of the following statements best reflects the critical message of the passage?
Answer (c) & explanation
The message is that solid waste management must be integrated with drainage and sewerage upkeep (c). Step 1: the passage says disease spreads when poor waste handling "combines with poor drainage" and sewage. So these must be managed together. That is (c). Step 2: option (a), drains not separated for sewage and storm water, is only a detail. Step 3: option (b), local bodies lack money and power, is not the main point. Option (d), drinking water shortage, is not discussed.
Tip: the message usually ties the passage's facts together. Here every fact links waste and drainage. Swachh Bharat Mission (Urban) 2.0 covers both solid waste and used-water management.
Answer as per the official UPSC answer key.
If you have two straight sticks of length 7·5 feet and 3·25 feet, what is the minimum length can you measure?
Answer (b) & explanation
The minimum length you can measure is 0·25 foot (b). Step 1: by adding and subtracting the two sticks, you can measure any multiple of their HCF, and nothing smaller. Step 2: write both in quarter-feet: 7·5 feet = 30 quarters; 3·25 feet = 13 quarters. Step 3: HCF(30, 13) = 1 quarter, which is 0·25 foot. For example, 30 − 2 × 13 = 4 quarters, and 13 − 3 × 4 = 1 quarter. Option (a), 0·05, is too small. Options (c) and (d) are not the minimum.
Tip: the smallest measurable length with two rods is their HCF. Convert decimals to whole units first to find it easily.
Answer as per the official UPSC answer key.
Read the passage
In India, authorities always look to store the maximum amount of water in reservoirs during the monsoon season, which is then used for irrigation and generation of electricity during the summer months. It is an internationally accepted practice that the water level of a reservoir should be kept below a certain level before the onset of monsoon season. This is so that when monsoon rains come, there is space to store the excess rainwater and also so that water can be released in a regulated manner. But the authorities store the maximum amount of water in reservoirs even before the close of the monsoon, only to ensure greater electricity generation and irrigation.
With reference to the above passage, the following assumptions have been made :
- 1. High risks involved in holding maximum water in reservoirs are due to our over-dependence on hydropower projects.
- 2. Storage capacity of dams should not be fully used before or during monsoon season.
- 3. Role of dams in flood control is underestimated in India.
Which of the above assumptions is/are valid?
Answer (d) & explanation
All three assumptions are valid (d). Step 1: the passage says reservoirs are filled early "only to ensure greater electricity generation and irrigation". So the risk comes from over-reliance on hydropower and storage (1). Step 2: it says space must be kept free for monsoon inflows. So dams should not be full before or during the monsoon (2). Step 3: by filling dams early, their flood-control role is ignored (3). So options (a), (b) and (c) fail.
Tip: Kerala's 2018 floods raised this debate: dams full before heavy rain had to release water suddenly. A dam's empty space is itself a flood shield.
Answer as per the official UPSC answer key.
Which one of the following will have minimum change in its value if 5 is added to both numerator and the denominator of the fractions 2/3, 3/4, 4/5 and 5/6?
Answer (d) & explanation
5/6 changes the least (d). Step 1: adding the same number to the top and bottom pulls a fraction towards 1. The fraction already closest to 1 moves the least. Step 2: among 2/3, 3/4, 4/5 and 5/6, the closest to 1 is 5/6. Step 3: check: 5/6 → 10/11, a change of 5/66 (about 0·076). 2/3 → 7/8, a change of 5/24 (about 0·21). So 5/6 changes least. Options (a), (b) and (c) change more.
Tip: the change for a/b with k added is k(b − a) ÷ [b(b + k)]. A bigger b means a smaller change, which favours 5/6.
Answer as per the official UPSC answer key.
Read the passage
People will invest in education whenever they are granted the economic freedom to fully enjoy its benefits. Again, this is for the obvious reason that the return on education increases as the level of economic freedom rises. When people, thanks to lower tax rates, are allowed to retain most of the higher income that they gain from each incremental level of education, it makes eminent sense to invest in education. On the other hand, when the government decides to tax the higher income of educated individuals at even higher rates, it makes very little sense to invest in educating oneself further. The same incentives apply to parents who decide on whether to invest in their children’s education.
With reference to the above passage, the following assumptions have been made :
- 1. Lower tax rates in a country invariably translate into greater investments in higher education.
- 2. Investment in the education of children ensures their economic freedom.
- 3. Economic freedom has a positive impact on building up human capital.
Which of the above assumptions is/are valid?
Answer (c) & explanation
Only assumption 3 is valid (c). Step 1: the passage says when people are free to keep the returns on their efforts, they invest in education. That builds human capital. So economic freedom helps human capital (3). Step 2: assumption 1 says lower taxes invariably lead to more investment in higher education. "Invariably" (always) overstates. Step 3: assumption 2 reverses the cause. The passage says freedom drives education, not that education ensures freedom. So options (a), (b) and (d) fail.
Tip: watch for reversed cause and effect. "A leads to B" does not mean "B leads to A". Also, "invariably" and "always" need very strong support.
Answer as per the official UPSC answer key.
In adult population of a city, 40% men and 30% women are married. What is the percentage of married adult population if no man marries more than one woman and no woman marries more than one man; and there are no widows and widowers?
Answer (c) & explanation
34 2/7% of adults are married (c). Step 1: each married man has one wife, so married men = married women. So 0·4M = 0·3W, which gives M : W = 3 : 4. Step 2: take M = 300 and W = 400. Married men = 40% of 300 = 120; married women = 30% of 400 = 120. Total married = 240 out of 700. Step 3: 240 ÷ 700 = 24/70 = 34 2/7%. Option (d), 35%, simply averages 40 and 30. Options (a) and (b) fail.
Tip: never average percentages of groups of different sizes. Find the group ratio first, then use real numbers.
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.
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.
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.