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.
(Same information as the question above.)
In how many different ways can a train travel from F to A without passing through any station more than once?
Answer (d) & explanation
There are 4 ways from F to A (d). Step 1: from F, the only way out is the two-way passage to D. B to F is one-way into F. Step 2: from D, a train can go to E or to H. Step 3: list the routes without repeating stations: F–D–E–A, F–D–E–C–A, F–D–E–G–C–A and F–D–H–G–C–A. That is 4 routes. Options (a), (b) and (c) undercount.
Tip: in route counting, branch at each station and follow every path to the end. Strike out paths that repeat a station or go the wrong way on a one-way passage. A neat tree diagram stops you missing any route.
Answer as per the official UPSC answer key.
Read the passage
A successful democracy depends upon widespread interest and participation in politics, in which voting is an essential part. To deliberately refrain from taking such an interest, and from voting, is a kind of implied anarchy; it is to refuse one’s political responsibility while enjoying the benefits of a free political society.
This passage relates to
Answer (a) & explanation
The passage is about the duty to vote (a). Step 1: it says not voting is "to refuse one's political responsibility". Responsibility means duty. So the passage stresses voting as a duty. That is option (a). Step 2: options (b) right to vote, (c) freedom to vote and (d) right to take part in politics all talk of rights or freedoms. Step 3: these options miss the passage's stress on obligation. A right can be used or left; a duty should be done.
Tip: in India voting is a legal right, not a legal duty. But passages often argue it is a moral duty. Read the tone words, like "responsibility", to decide.
Answer as per the official UPSC answer key.
A bag contains 20 balls. 8 balls are green, 7 are white and 5 are red. What is the minimum number of balls that must be picked up from the bag blindfolded (without replacing any of it) to be assured of picking at least one ball of each colour?
Answer (b) & explanation
You must pick 16 balls (b). Step 1: think of the worst case: the balls come out in the most unlucky order. Step 2: the unluckiest order gives all the balls of the two largest colours first: all 8 green and all 7 white. That is 15 balls with no red yet. Step 3: the 16th ball must be red, since only red balls are left. So 16 balls guarantee at least one of each colour. Option (a), 17, is more than needed. Option (c), 13, and option (d), 11, could still miss a colour.
Tip: for "to be sure" questions, assume the worst luck. Take all of the biggest groups first, then add one more ball.
Answer as per the official UPSC answer key.
Read the passage
During the summer in the Arctic Ocean, sea ice has been melting earlier and faster, and the winter freeze has been coming later. In the last three decades, the extent of summer ice has declined by about 30 per cent. The lengthening period of summer melt threatens to undermine the whole Arctic food web, atop which stand polar bears.
Which among the following is the most crucial message conveyed by the above passage?
Answer (d) & explanation
The crucial message is that climate change threatens the survival of polar bears (d). Step 1: the passage says the longer melt season "threatens to undermine the whole Arctic food web, atop which stand polar bears". So the bears' survival is at risk. Step 2: option (a) says Arctic summer is getting shorter. The passage says it is getting longer. Step 3: option (c) reverses cause and effect: the food web supports the bears, not the other way round. Option (b), moving bears to the South Pole, is never suggested.
Tip: watch for options that flip a fact (longer to shorter) or reverse a cause. These small changes are common traps.
Answer as per the official UPSC answer key.
There are thirteen 2-digit consecutive odd numbers. If 39 is the mean of the first five such numbers, then what is the mean of all the thirteen numbers?
Answer (a) & explanation
The mean of all thirteen numbers is 47 (a). Step 1: for evenly spaced numbers, the mean equals the middle term. The first five have mean 39, so 39 is their middle (3rd) number. The five are 35, 37, 39, 41 and 43. Step 2: the thirteen numbers start at 35 and go up by 2: 35, 37, … up to 59. Step 3: their middle term is the 7th one: 35 + 6 × 2 = 47. So the mean is 47. Options (b) 49 and (c) 51 are too high. Option (d), 45, is too low.
Tip: in any evenly spaced list, mean = middle term = (first + last) ÷ 2. Here (35 + 59) ÷ 2 = 47, which checks out.
Answer as per the official UPSC answer key.
Read the passage
Really I think that the poorest he that is in England has a life to live, as the greatest he, and therefore truly, I think it is clear that every man that is to live under a government ought first by his own consent to put himself under the government, and I do think that the poorest man in England is not at all bound in a strict sense to that government that he has not had a voice to put himself under.
The above statement argues for
Answer (b) & explanation
The statement argues for rule by the consent of the governed (b). Step 1: it says every man should live under a government only "by his own consent". That is government by consent. Option (b) states it. Step 2: the statement mentions "the poorest man" to show that even he has equal standing. It does not ask for rule of the poor (c). Step 3: options (a) equal wealth and (d) taking property from the rich are about money, which the statement does not discuss.
Tip: this idea comes from the Putney Debates in 17th-century England. "Consent of the governed" is the base of modern democracy, where people elect their rulers.
Answer as per the official UPSC answer key.
The sum of income of A and B is more than that of C and D taken together. The sum of income of A and C is the same as that of B and D taken together. Moreover, A earns half as much as the sum of the income of B and D. Whose income is the highest?
Answer (b) & explanation
B has the highest income (b). Step 1: A earns half of B + D, so B + D = 2A. Also A + C = B + D, so A + C = 2A, which gives C = A. Step 2: A + B > C + D. Since C = A, this becomes B > D. Step 3: B + D = 2A and B > D, so B is above A and D is below A. So B > A = C > D, and B is highest. Option (a) A and option (c) C are equal and in the middle. Option (d) D is the lowest.
Tip: turn each sentence into an equation and substitute step by step. Finding that two people earn the same simplifies everything else.
Answer as per the official UPSC answer key.
Read the passage
Climate change is likely to expose a large number of people to increasing environmental risks forcing them to migrate. The international community is yet to recognize this new category of migrants. There is no consensus on the definition and status of climate refugees owing to the distinct meaning the term refugees carry under international laws. There are still gaps in understanding how climate change will work as the root cause of migration. Even if there is recognition of climate refugees, who is going to provide protection? More emphasis has been given to international migration due to climate change. But there is a need to recognize the migration of such people within the countries also so that their problems can be addressed properly.
Which of the following is the most rational inference from the above passage?
Answer (d) & explanation
The rational inference is that the link between climate change and migration is not yet properly understood (d). Step 1: the passage says: "there are still gaps in understanding how climate change will work as the root cause of migration". That is option (d). Step 2: option (c) calls climate change the most important reason for future migration. The passage never ranks it. Step 3: option (a), that the world cannot cope with climate refugees, is not stated. Option (b), stopping climate change, is a call to action the passage does not make.
Tip: when a passage admits "gaps in understanding", the safe inference is that the issue is uncertain. Options that claim certainty, like "most important", go too far.
Answer as per the official UPSC answer key.
(Same information as the question above.)
If the route between G and C is closed, which one of the following stations need not be passed through while travelling from H to C?
Answer (c) & explanation
Station A need not be passed (c). Step 1: with the G to C passage closed, find a way from H to C. From H, the only way out is the one-way passage H to G. Step 2: from G, the only way out now is G to B (two-way). From B: one-way B to F. From F: F to D. From D: D to E. From E: one-way E to C. Step 3: the only route is H → G → B → F → D → E → C. Station A is not on it. Options (a) E, (b) D and (d) B are all on the route.
Tip: when a passage is closed, re-draw just that part of the map. Then trace the only path left; stations off it are the answer.
Answer as per the official UPSC answer key.
Read the passage
In a free country, the man who reaches the position of leader is usually one of outstanding character and ability. Moreover, it is usually possible to foresee that he will reach such a position, since early in life one can see his qualities of character. But this is not always true in the case of a dictator; often he reaches his position of power through chance, very often through the unhappy state of his country.
The passage seems to suggest that:
Answer (d) & explanation
The passage suggests that despair in a country sometimes leads to dictatorship (d). Step 1: it says a dictator often rises "through the unhappy state of his country". So a nation's despair can open the way to a dictator. That is option (d). Step 2: option (a) says the leader foresees his own rise. But in the passage it is others who foresee it. Step 3: option (b) says leaders are chosen only by free countries, which is too extreme. Option (c), that a leader must free his country from despair, is not the point.
Tip: history fits this idea; hard times in Germany helped Hitler rise. But always answer from the passage first.
Answer as per the official UPSC answer key.
If 2 boys and 2 girls are to be arranged in a row so that the girls are not next to each other, how many possible arrangements are there?
Answer (c) & explanation
There are 12 arrangements (c). Step 1: four different children can stand in 4 × 3 × 2 × 1 = 24 orders. Step 2: count the orders with the girls together. Tie the 2 girls into one block. Now there are 3 items, which can be arranged in 3 × 2 × 1 = 6 ways. The girls can swap inside the block, so × 2 = 12. Step 3: girls apart = 24 − 12 = 12. Option (d), 24, counts all orders. Option (b), 6, and option (a), 3, undercount.
Tip: for "not next to each other", count all orders and subtract those where they are together. Treating a pair as one block makes the "together" count easy.
Answer as per the official UPSC answer key.
Read the passage
Why do people prefer open defecation and not want toilets or, if they have them, only use them sometimes? Recent research has shown two critical elements : ideas of purity and pollution, and not wanting pits or septic tanks to fill because they have to be emptied. These are the issues that nobody wants to talk about, but if we want to eradicate the practice of open defecation, they have to be confronted and dealt properly.
Which among the following is the most crucial message conveyed by the above passage?
Answer (b) & explanation
The crucial message is that people must see toilet use and pit-emptying as clean, not polluting (b). Step 1: the passage says ideas of purity and pollution, and the dislike of emptying pits, "have to be confronted". So people's view of toilets must change. That is option (b). Step 2: options (a) and (c) say these ideas cannot be removed and people cannot change. That contradicts the call to act. Step 3: option (d), that people have no civic sense or privacy, is not the passage's claim.
Tip: when the author says something "has to be" done, the author believes change is possible. So options saying "cannot" go against the author. Swachh Bharat faced exactly this behaviour challenge.
Answer as per the official UPSC answer key.
Six boys A, B, C, D, E and F play a game of cards. Each has a pack of 10 cards. F borrows 2 cards from A and gives away 5 to C who in turn gives 3 to B while B gives 6 to D who passes on 1 to E. Then the number of cards possessed by D and E is equal to the number of cards possessed by
Answer (b) & explanation
D and E together have as many cards as B, C and F (b). Step 1: everyone starts with 10. F borrows 2 from A: A 8, F 12. F gives 5 to C: F 7, C 15. Step 2: C gives 3 to B: C 12, B 13. B gives 6 to D: B 7, D 16. D gives 1 to E: D 15, E 11. Step 3: final count: A 8, B 7, C 12, D 15, E 11, F 7. D + E = 26. B + C + F = 7 + 12 + 7 = 26. Option (a) gives 27. Option (c) gives 22. Option (d) gives 27.
Tip: track each person's count after every move in a small table. Check that the total stays 60; if not, you have made a slip.
Answer as per the official UPSC answer key.
The average rainfall in a city for the first four days was recorded to be 0·40 inch. The rainfall on the last two days was in the ratio of 4 : 3. The average of six days was 0·50 inch. What was the rainfall on the fifth day?
Answer (c) & explanation
Rainfall on the fifth day was 0.80 inch (c). Step 1: total over six days = 6 × 0.50 = 3.00 inches. Total over the first four days = 4 × 0.40 = 1.60 inches. Step 2: so the last two days had 3.00 − 1.60 = 1.40 inches. Step 3: these are in the ratio 4 : 3. 1.40 ÷ 7 = 0.20, so the fifth day = 4 × 0.20 = 0.80 inch and the sixth = 0.60 inch. Option (a), 0.60, is the sixth day. Options (b) and (d) do not fit.
Tip: in average questions, turn every average into a total first. Then subtract to find the missing part, and split it by the ratio.
Answer as per the official UPSC answer key.
Consider the following :
Statement : Good voice is a natural gift but one has to keep practising to improve and excel well in the field of music.
Conclusions :
- I. Natural gifts need nurturing and care.
- II. Even though one's voice is not good, one can keep practising.
Which one of the following is correct in respect of the above statement and conclusions?
Answer (a) & explanation
Only conclusion I follows (a). Step 1: the statement says a good voice is a natural gift, but one must keep practising to excel. So even a natural gift needs work and care. That is conclusion I. Step 2: conclusion II is about people without a good voice practising. The statement says nothing about such people. So II does not follow. Step 3: so option (b), only II, and option (c), either I or II, fail. Option (d), neither, fails because I follows.
Tip: a conclusion must stay within what the statement talks about. If the statement is only about people with good voices, you cannot conclude anything about people without them.
Answer as per the official UPSC answer key.
Read the passage
Many farmers use synthetic pesticides to kill infesting insects. The consumption of pesticides in some of the developed countries is touching 3000 grams/hectare. Unfortunately, there are reports that these compounds possess inherent toxicities that endanger the health of the farm operators, consumers and the environment. Synthetic pesticides are generally persistent in environment. Entering in food chain they destroy the microbial diversity and cause ecological imbalance. Their indiscriminate use has resulted in development of resistance among insects to insecticides, upsetting of balance in nature and resurgence of treated populations. Natural pest control using the botanical pesticides is safer to the user and the environment because they break down into harmless compounds within hours or days in the presence of sunlight. Plants with pesticidal properties have been in nature for millions of years without any ill or adverse effects on the ecosystem. They are easily decomposed by many microbes common in most soils. They help in the maintenance of biological diversity of predators and the reduction of environmental contamination and human health hazards. Botanical pesticides formulated from plants are biodegradable and their use in crop protection is a practical sustainable alternative.
On the basis of the above passage, the following assumptions have been made :
- 1. Synthetic pesticides should never be used in modern agriculture.
- 2. One of the aims of sustainable agriculture is to ensure minimal ecological imbalance.
- 3. Botanical pesticides are more effective as compared to synthetic pesticides.
Which of the assumptions given above is/are correct?
Answer (b) & explanation
Only assumption 2 is correct (b). Step 1: the passage calls botanical pesticides the "sustainable alternative" because they avoid ecological imbalance. So one aim of sustainable farming is minimal imbalance. Assumption 2 holds. Step 2: assumption 1 says synthetic pesticides should never be used. But the passage faults "indiscriminate use", not all use. Step 3: assumption 3 says botanicals are more effective. The passage compares their safety, not their power. So 1 and 3 fail, and options (a), (c) and (d) fail.
Tip: separate "safer" from "more effective". Neem-based pesticides are safer for people and nature, but the passage never says they kill pests better.
Answer as per the official UPSC answer key.
There are certain 2-digit numbers. The difference between the number and the one obtained on reversing it is always 27. How many such maximum 2-digit numbers are there?
Answer (d) & explanation
None of the options is right (d). Step 1: number − reverse = 9 × (difference of the digits). For a difference of 27, the digits must differ by 3. Step 2: numbers where the tens digit is 3 more than the units digit: 41, 52, 63, 74, 85 and 96. That is 6. Their reverses (14, 25, 36, 47, 58, 69) also differ by 27, if we allow the difference either way, giving 12. Step 3: 30 has reverse 03, which is not a 2-digit number. So the count is 6 or 12, never 3, 4 or 5. Options (a), (b) and (c) fail.
Tip: learn that any 2-digit number minus its reverse is a multiple of 9.
Answer as per the official UPSC answer key.
Read the passage
The greatest blessing that technological progress has in store for mankind is not, of course, an accumulation of material possessions. The amount of these that can be effectively enjoyed by one individual in one lifetime is not great. But there is not the same narrow limit to the possibilities of the enjoyment of leisure. The gift of leisure may be abused by people who have had no experience of making use of it. Yet the creative use of leisure by a minority in societies has been the mainspring of all human progress beyond the primitive level.
With reference to the above passage, the following assumptions have been made :
- 1. People always see the leisure time as a gift and use it for acquiring more material possessions.
- 2. Use of leisure by some people to produce new and original things has been the chief source of human progress.
Which of these assumptions is/are valid?
Answer (b) & explanation
Only assumption 2 is valid (b). Step 1: the passage says "the creative use of leisure by a minority… has been the mainspring of all human progress". So some people using leisure to create new things drove progress. Assumption 2 holds. Step 2: assumption 1 says people always see leisure as a gift and use it to gain more possessions. But the passage warns leisure "may be abused", and it does not call possessions the blessing. Step 3: so assumption 1 fails, and options (a), (c) and (d) fail.
Tip: "always" in a statement is a warning sign. If the passage admits even one exception, like leisure being abused, "always" is false.
Answer as per the official UPSC answer key.
The outer surface of a 4 cm × 4 cm × 4 cm cube is painted completely in red. It is sliced parallel to the faces to yield sixty four 1 cm × 1 cm × 1 cm small cubes. How many small cubes do not have painted faces?
Answer (a) & explanation
8 small cubes have no painted face (a). Step 1: the 4 × 4 × 4 cube is cut into 64 small cubes. Only the outer layer is painted. Step 2: the unpainted cubes form an inner block. Remove one layer from each side: 4 − 2 = 2 cubes along each edge. Step 3: the inner block is 2 × 2 × 2 = 8 cubes. Option (c), 24, is the number with exactly one painted face. Option (b), 16, and option (d), 36, do not fit.
Tip: for an n × n × n painted cube, unpainted = (n − 2)³, one face = 6(n − 2)², two faces = 12(n − 2), and three faces = 8. Learn these four formulas.
Answer as per the official UPSC answer key.
Read the passage
In the last two decades, the world’s gross domestic product (GDP) has increased by 50 per cent, whereas inclusive wealth has increased by a mere 6 per cent. In recent decades, GDP-driven economic performance has only harmed inclusive wealth like human capital; and natural capital like forests, land and water. While the world’s human capital which stands at 57 per cent of total inclusive wealth grew by only 8 per cent, the natural capital which is 23 per cent of total inclusive wealth declined by 30 per cent worldwide in the last two decades.
Which of the following is the most crucial inference from the above passage?
Answer (b) & explanation
The crucial inference is that growth driven by GDP alone is neither desirable nor sustainable (b). Step 1: the passage says GDP rose about 50%, but inclusive wealth rose only 6%, and natural capital fell about 30%. So GDP growth hid a loss of real wealth. Step 2: this means GDP-only growth is not sustainable, which is option (b). Step 3: options (a) and (d) each pick one part of the argument, natural or human capital. Option (c), that world economic performance is unsatisfactory, is too vague.
Tip: inclusive wealth counts natural, human and produced capital together. A rising GDP with falling natural capital means a country is spending its savings.
Answer as per the official UPSC answer key.