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.
Eight students A, B, C, D, E, F, G and H sit around a circular table, equidistant from each other, facing the centre of the table, not necessarily in the same order. B and D sit neither adjacent to C nor opposite to C. A sits in between E and D, and F sits in between B and H. Which one of the following is definitely correct?
Answer (d) & explanation
None of the options is definitely correct (d). Step 1: the blocks are E–A–D and B–F–H. C must not sit next to or opposite B or D. Step 2: several seatings meet all the rules. For example, going round: A, D, G, C, H, F, B, E. Step 3: in this seating, B is not between A and G (a fails), C is not opposite G (b fails) and E is not opposite F (c fails). Since one valid seating breaks each option, none is definite.
Tip: for "definitely correct", find one valid arrangement that breaks the option. One counter-example is enough to reject it.
'definitely correct' means true in every possible seating. One valid seating where it fails is enough to reject it.
Answer as per the official UPSC answer key.
Read the passage
To encourage research is one of the functions of a university. Contemporary universities have encouraged research, not only in those cases where research is necessary, but on all sorts of entirely unprofitable subjects as well. Scientific research is probably never completely valueless. However silly and insignificant it may seem, however mechanical and unintelligent the labours of the researchers, there is always a chance that the results may be of value to the investigator of talent, who can use the facts collected for him by uninspired but industrious researchers as the basis of some fruitful generalization. But where research is not original, but consists in the mere rearrangement of existing materials, where its object is not scientific but literary or historical, then there is a risk of the whole business becoming merely futile.
According to the author
Answer (c) & explanation
Any research result can be of value to an intelligent investigator (c). Step 1: the passage says "there is always a chance that the results may be of value" to a talented investigator. Step 2: "chance" and "may" mean any result can help. That is (c). Step 3: options (b) and (d) turn a chance into a certainty ("always valuable", "must always be"). Option (a), not many results are useful, goes against the passage.
Tip: words like "may", "chance" and "can" signal possibility. Reject options that turn possibility into certainty.
Answer as per the official UPSC answer key.
Consider the Question and two Statements given below :
Question : Is x an integer?
Statement-1 : x/3 is not an integer.
Statement-2 : 3x is an integer.
Which one of the following is correct in respect of the Question and the Statements?
Answer (d) & explanation
Even both statements together are not enough (d). Step 1: test a value that fits both statements: x = 1. Then 1/3 is not an integer, and 3 × 1 = 3 is an integer. Here x is an integer. Step 2: test x = 1/3. Then 1/9 is not an integer, and 3 × 1/3 = 1 is an integer. Here x is not an integer. Step 3: both statements hold in each case, but the answer differs. So they are not sufficient. Options (a), (b) and (c) fail.
Tip: in data sufficiency, try fractions and negative numbers too. Two allowed values giving different answers prove the data insufficient.
in this older format, (d) means "even together not sufficient".
Answer as per the official UPSC answer key.
Read the passage
In an economic organization, allowing mankind to benefit by the productivity of machines should lead to a very good life of leisure, and much leisure is apt to be tedious except to those who have intelligent activities and interests. If a leisured population is to be happy, it must be an educated population, and must be educated with a view to enjoyment as well as to the direct usefulness of technical knowledge.
Which of the following statements best reflects the underlying tone of the passage?
Answer (a) & explanation
The underlying tone is that only an educated population can best use the benefits of economic progress (a). Step 1: the passage says machines can give people much leisure, but leisure is tedious except for those with intelligent interests. Step 2: so a happy leisured population "must be an educated population". Education turns progress into a good life. That is (a). Step 3: option (c) turns this into a general rule that more education always means more happiness, which is not said. Options (b) and (d) make leisure the aim, which the passage does not argue.
Tip: this is from Bertrand Russell. Pick the option that keeps the passage's condition ("must be educated"), not one that reverses it.
Answer as per the official UPSC answer key.
Three persons A, B and C are standing in a queue not necessarily in the same order. There are 4 persons between A and B, and 7 persons between B and C. If there are 11 persons ahead of C and 13 behind A, what could be the minimum number of persons in the queue?
Answer (a) & explanation
The minimum is 22 persons (a). Step 1: 11 people are ahead of C, so C is 12th. Step 2: 7 people stand between B and C. So B is 4th or 20th. To keep the queue short, take B = 4th. Step 3: 4 people stand between A and B. A cannot be before 1st, so A is 9th. 13 people are behind A, so the queue has 9 + 13 = 22. C at 12th lies inside it. Options (b), (c) and (d) come from other, longer placements.
Tip: for a minimum, place people as close to the front as the rules allow, then check every condition.
Taking B = 20th pushes A to 15th or 25th and gives 28 or more.
Answer as per the official UPSC answer key.
Read the passage
The majority of people who fail to accumulate money sufficient for their needs, are generally, easily influenced by the opinions of others. They permit the newspapers and the gossiping neighbours to do their thinking for them. Opinions are the cheapest commodities on the earth. Everyone has a flock of opinions ready to be wished upon by anyone who will accept them. If you are influenced by opinions when you reach decisions, you will not succeed in any undertaking.
What is the main idea of the passage?
Answer (a) & explanation
The main idea is that people should not be influenced by others' opinions (a). Step 1: the passage says people who fail to save let newspapers and neighbours think for them. Opinions are "the cheapest commodities". Step 2: it ends: if opinions influence your decisions, "you will not succeed". So don't be swayed by them. That is (a). Step 3: option (b), save as much as you can, is not the point. Option (c) says never give or take opinions, which goes too far. Option (d) turns the warning into a guarantee of success.
Tip: "If you do X, you will fail" does not mean "If you avoid X, you will succeed". Watch for this reversal trap.
Answer as per the official UPSC answer key.
Which number amongst 240, 321, 418 and 812 is the smallest?
Answer (b) & explanation
3²¹ is the smallest (b). Step 1: write the powers of 2, 4 and 8 in base 2. 4¹⁸ = 2³⁶ and 8¹² = 2³⁶. So (c) and (d) are equal, and both are smaller than 2⁴⁰ (a). Step 2: compare 3²¹ with 2³⁶. Make the powers equal: 3²¹ = (3⁷)³ = 2187³, and 2³⁶ = (2¹²)³ = 4096³. Step 3: 2187 is less than 4096, so 3²¹ is the smallest. Options (a), (c) and (d) are larger.
Tip: to compare powers, change them to the same base or the same exponent. Also note that two equal options can never be "the smallest" alone.
Answer as per the official UPSC answer key.
Read the passage
For two or three generations past, ever-increasing numbers of individuals have been living as workers merely, not as human beings. An excessive amount of labour is rule today in every circle of society, with the result that man’s spiritual element cannot thrive. He finds it very difficult to spend his little leisure in serious activities. He does not want to think; or he cannot even if he wants to. He seeks not self-improvement, but entertainment which would enable him to be mentally idle and to forget his usual activities. Therefore, the so-called culture of our age is dependant more on cinema than on theatre, more on newspapers, magazines and crime stories than on serious literature.
The passage is based on the idea that
Answer (b) & explanation
The passage is based on the idea that overstrain is the great evil of our age (b). Step 1: the passage says "an excessive amount of labour" is the rule today. Step 2: everything else follows from this: man's spiritual side cannot grow, he has little leisure, and he seeks only entertainment. So overwork is the root idea. That is (b). Step 3: option (a), man should not work hard, overstates it; the problem is excess. Options (c) and (d) are effects of overwork, not the main idea.
Tip: separate the root cause from its effects. The base idea is the cause the author keeps returning to.
Answer as per the official UPSC answer key.
Read the passage
How best can the problems of floods and droughts be addressed so that the losses are minimal and the system becomes resilient? In this context, one important point that needs to be noted is that India gets ‘too much’ water (about 75% of annual precipitation) during 120 days (June to September) and ‘too little’ for the remaining 245 days. This skewed water availability has to be managed and regulated for its consumption throughout the year.
Which one of the following best reflects the practical, rational and lasting solution?
Answer (d) & explanation
The lasting solution is buffer stocking of water through dams and recharging aquifers (d). Step 1: the passage says India gets about 75% of its rain in 120 days (June to September) and too little in the other 245 days. Step 2: the problem is timing, so water must be stored for year-round use. Dams store surface water and recharged aquifers store groundwater. That is (d). Step 3: canals (a) and river interlinking (c) mainly move water across places, not across seasons. Option (b), changing crops, does not store water.
Tip: match the solution to the problem. A time problem (seasons) needs storage; a place problem needs transfer.
Answer as per the official UPSC answer key.
The increase in the price of a certain item was 25%. Then the price was decreased by 20% and then again increased by 10%. What is the resultant increase in the price?
Answer (b) & explanation
The resultant increase is 10% (b). Step 1: start with a price of ₹ 100. A 25% rise makes it ₹ 125. Step 2: a 20% cut on 125 is ₹ 25, bringing it to ₹ 100. Step 3: a 10% rise on 100 makes it ₹ 110. From ₹ 100 to ₹ 110 is a rise of 10%. Option (d), 15%, wrongly adds 25 − 20 + 10. Options (a) and (c) are other miscalculations.
Tip: multiply the factors: 1.25 × 0.8 × 1.1 = 1.1. A 25% rise followed by a 20% cut always cancels out exactly.
(d) 15% just adds 25 − 20 + 10. Each change works on the new price.
Answer as per the official UPSC answer key.
Read the passage
If presents bring less thrill now that we are grown up, perhaps it is because we have too much already; or perhaps it is because we have lost the fullness of the joy of giving, and with it the fullness of the joy of receiving. Children’s fears are poignant, their miseries are acute, but they do not look too forward nor too far backward. Their joys are clear and complete, because they have not yet learnt always to add ‘but’ to every proposition. Perhaps we are too cautious, too anxious, too sceptical. Perhaps some of our cares would shrink if we thought less about them and entered with more single-minded enjoyment into the happiness that come our way.
With reference to the passage, which one of the following statements is correct?
Answer (b) & explanation
The correct statement is that there can be more than one reason adults feel less thrilled by presents (b). Step 1: the author offers two "perhaps" reasons: we have too much already, or we have lost the full joy of giving. Step 2: more than one possible reason means (b). Step 3: option (a) says adults can never be thrilled. But the passage says "less thrill", not none. Option (c) is wrong because the author does suggest reasons. Option (d), less capacity for love, is not said.
Tip: "perhaps ... or perhaps ..." signals several possible reasons. "Less" thrill never means "no" thrill.
Answer as per the official UPSC answer key.
Read the passage
Natural selection cannot anticipate future environments on the earth. Therefore, the set of existing organisms can never be fully prepared for environmental catastrophes that await life. An outcome of this is the extinction of those species which cannot overcome environmental adversity. This failure to survive, in modern terms, can be attributed to the genomes which are unable to withstand geological vagaries or biological mishaps (infections, diseases and so on). In biological evolution on the earth, extinction of species has been a major feature. The earth may presently have up to ten million species, yet more than 90% of species that have ever lived on the earth are now extinct. Once again, the creationist doctrines fail to satisfactorily address why a divine creator will firstly bother to create millions of species and then allow them to perish. The Darwinian explanation for extinct life is once again simple, elegant and at once convincing—organisms go extinct as a function of environmental or biological assaults for which their inheritance deems them ill-equipped. Therefore, the so-called Darwinian theory of evolution is not a theory at all. Evolution happens—this is a fact. The mechanism of evolution (Darwin proposed natural selection) is amply supported by scientific data. Indeed, to date no single zoological, botanical, geological, paleontological, genetic or physical evidence has refuted either of the central two main Darwinian ideas. If religion is not taken into consideration, Darwinian laws are acceptable just like the laws proposed by Copernicus, Galileo, Newton and Einstein—sets of natural laws that explain natural phenomena in the universe.
According to the passage, natural selection cannot anticipate future environments on the earth as
- 1. species not fully prepared to face the environmental changes that await them will face extinction
- 2. all the existing species would get extinct as their genomes will not withstand biological mishaps
- 3. inability of the genome to withstand environmental changes would result in extinction
- 4. extinction of species is a common feature
Select the correct answer using the code given below.
Answer (c) & explanation
Statements 1, 3 and 4 follow (c). Step 1: the passage says organisms "can never be fully prepared" for coming catastrophes, so unprepared species die out (1). Step 2: it blames genomes that cannot withstand geological vagaries or biological mishaps (3). It calls extinction "a major feature" of evolution (4). Step 3: statement 2 says all existing species will go extinct. The passage never claims this; it only says those that cannot cope die out. So options (a), (b) and (d), which include 2, fail.
Tip: "all" is the giveaway. The passage says more than 90% of species that ever lived are extinct, not that every species will be.
Answer as per the official UPSC answer key.
Read the passage
“The social order is a sacred right which is the basis of all other rights. Nevertheless, this right does not come from nature, and must therefore be founded on conventions.”
With reference to the above passage, which of the following statements is/are correct?
- 1. Conventions are the sources of rights of man.
- 2. Rights of man can be exercised only when there is a social order.
Select the correct answer using the code given below.
Answer (c) & explanation
Both statements are correct (c). Step 1: the passage says the social order is "the basis of all other rights" and it "must be founded on conventions". Step 2: if all rights rest on the social order, and the social order rests on conventions, then conventions are the source of rights (1). Step 3: if the social order is the basis of all rights, rights can work only when a social order exists (2). So options (a), (b) and (d) fail.
Tip: this is Rousseau's Social Contract. Follow the chain: conventions → social order → rights.
Answer as per the official UPSC answer key.
The digits 1 to 9 are arranged in three rows in such a way that each row contains three digits, and the number formed in the second row is twice the number formed in the first row; and the number formed in the third row is thrice the number formed in the first row. Repetition of digits is not allowed. If only three of the four digits 2, 3, 7 and 9 are allowed to use in the first row, how many such combinations are possible to be arranged in the three rows?
Answer (c) & explanation
Two arrangements are possible (c). Step 1: the third row is 3 × the first row and must stay a 3-digit number. So the first row is at most 329. Using three of 2, 3, 7, 9, the choices are 237, 239, 273, 279, 293, 297, 327 and 329. Step 2: check that all nine digits 1 to 9 appear once. 273 → 546 → 819 works. 327 → 654 → 981 works. Step 3: the others repeat a digit or produce a 0. So there are 2. Options (a), (b) and (d) miscount.
Tip: first use a size limit (×3 below 1000) to shrink the list. Then test the few candidates left.
Answer as per the official UPSC answer key.
Read the passage
For two or three generations past, ever-increasing numbers of individuals have been living as workers merely, not as human beings. An excessive amount of labour is rule today in every circle of society, with the result that man’s spiritual element cannot thrive. He finds it very difficult to spend his little leisure in serious activities. He does not want to think; or he cannot even if he wants to. He seeks not self-improvement, but entertainment which would enable him to be mentally idle and to forget his usual activities. Therefore, the so-called culture of our age is dependant more on cinema than on theatre, more on newspapers, magazines and crime stories than on serious literature.
Man does not seek self-improvement because he
Answer (d) & explanation
Man does not seek self-improvement because he loves amusement and is mentally idle (d). Step 1: the passage says he seeks "not self-improvement, but entertainment which would enable him to be mentally idle". That is (d). Step 2: option (b) says he has no time. But the passage says he has "little leisure", not none. Step 3: option (a), lack of intellect, is not said; the passage says he does not want to think. Option (c), materialism, is not mentioned.
Tip: "little" is not "no". UPSC often swaps a mild word in the passage for an absolute one in the options.
Answer as per the official UPSC answer key.
If 15 × 14 × 13 × … × 3 × 2 × 1 = 3m × n where m and n are positive integers, then what is the maximum value of m?
Answer (b) & explanation
The maximum value of m is 6 (b). Step 1: count how many times 3 divides 15!. Multiples of 3 up to 15: 3, 6, 9, 12, 15. That gives 5 threes. Step 2: 9 = 3 × 3 has an extra 3. That adds 1 more. Step 3: m = 5 + 1 = 6. Option (c), 5, forgets the extra 3 in 9. Options (a) and (d) miscount.
Tip: to count a prime p in n!, add n/p + n/p² + ... (whole parts only). Here 15/3 + 15/9 = 5 + 1 = 6.
don't forget the extra 3 in 9.
Answer as per the official UPSC answer key.
Read the passage
In some places in the world, the productivity of staples such as rice and wheat has reached a plateau. Neither new strains nor fancy agrochemicals are raising the yields. Nor is there much unfarmed land left that is suitable to be brought under the plough. If global temperature continues to rise, some places will become unsuitable for farming. Application of technology can help overcome these problems. Agricultural technology is changing fast. Much of this change is brought about by affluent farmers in the West/Americas. Techniques developed in the West are being adapted in some places to make tropical crops more productive. Technology is of little use if it is not adapted. In the developing world, that applies as much to existing farming techniques as it does to the latest advances in genetic modification. Extending to the smallholders and subsistence farmers of Africa and Asia the best of today’s agricultural practices, in such simple matters as how much fertilizers to apply and when, would lead to a greatly increased availability of food for humanity. So would things like better roads and storage facilities, to allow for the carriage of surpluses to markets and reduce wastage.
Based on the above passage, the following assumptions have been made :
- 1. Development of agricultural technology is confined to developed countries.
- 2. Agricultural technology is not adapted in developing countries.
Which of the above assumptions is/are valid?
Answer (d) & explanation
Neither assumption is valid (d). Step 1: the passage says "much of" the change in farm technology comes from the West. "Much of" is not "all of", so technology is not confined to developed countries (1 fails). Step 2: it says Western techniques "are being adapted in some places" to make tropical crops more productive. So statement 2, that technology is not adapted in developing countries, is false. Step 3: so options (a), (b) and (c) fail.
Tip: watch absolute words like "confined" and "not adapted". One line saying "much of" or "some places" is enough to reject them.
Answer as per the official UPSC answer key.
Read the passage
If presents bring less thrill now that we are grown up, perhaps it is because we have too much already; or perhaps it is because we have lost the fullness of the joy of giving, and with it the fullness of the joy of receiving. Children’s fears are poignant, their miseries are acute, but they do not look too forward nor too far backward. Their joys are clear and complete, because they have not yet learnt always to add ‘but’ to every proposition. Perhaps we are too cautious, too anxious, too sceptical. Perhaps some of our cares would shrink if we thought less about them and entered with more single-minded enjoyment into the happiness that come our way.
The author of the passage is against
Answer (a) & explanation
The author is against worrying too much about the past and future (a). Step 1: the passage says children's joys are complete because they "do not look too forward nor too far backward". Step 2: it adds that our cares might shrink "if we thought less about them". So the author is against too much worrying about past and future. That is (a). Step 3: option (b), thinking about presents, misreads the word "presents". Options (c) and (d) are not what the author criticises.
Tip: here "presents" means gifts, not the present time. Read the wording closely; UPSC builds traps on such double meanings.
Answer as per the official UPSC answer key.
Read the passage
Natural selection cannot anticipate future environments on the earth. Therefore, the set of existing organisms can never be fully prepared for environmental catastrophes that await life. An outcome of this is the extinction of those species which cannot overcome environmental adversity. This failure to survive, in modern terms, can be attributed to the genomes which are unable to withstand geological vagaries or biological mishaps (infections, diseases and so on). In biological evolution on the earth, extinction of species has been a major feature. The earth may presently have up to ten million species, yet more than 90% of species that have ever lived on the earth are now extinct. Once again, the creationist doctrines fail to satisfactorily address why a divine creator will firstly bother to create millions of species and then allow them to perish. The Darwinian explanation for extinct life is once again simple, elegant and at once convincing—organisms go extinct as a function of environmental or biological assaults for which their inheritance deems them ill-equipped. Therefore, the so-called Darwinian theory of evolution is not a theory at all. Evolution happens—this is a fact. The mechanism of evolution (Darwin proposed natural selection) is amply supported by scientific data. Indeed, to date no single zoological, botanical, geological, paleontological, genetic or physical evidence has refuted either of the central two main Darwinian ideas. If religion is not taken into consideration, Darwinian laws are acceptable just like the laws proposed by Copernicus, Galileo, Newton and Einstein—sets of natural laws that explain natural phenomena in the universe.
The passage suggests that Darwinian theory of evolution is not a theory at all because
Answer (b) & explanation
UPSC's key gives (b): extinction is a function of environment and biological assaults. Step 1: the passage says organisms "go extinct as a function of environmental or biological assaults". Step 2: the very next line says "Therefore", Darwinian theory is "not a theory at all". UPSC links the "therefore" to this line. The author means evolution is a fact, not just a theory. Step 3: option (c), no evidence to refute it, comes later in the passage. Options (a) and (d) are creationist ideas the author rejects.
Tip: when a question asks "because", look for the line just before "therefore". Here the author argues evolution is so well shown that it is a fact.
Answer as per the official UPSC answer key.
Two candidates X and Y contested an election. 80% of voters cast their vote and there were no invalid votes. There was no NOTA (None of the above) option. X got 56% of the votes cast and won by 1440 votes. What is the total number of voters in the voters list?
Answer (a) & explanation
The voters list has 15000 names (a). Step 1: there are only two candidates and no invalid votes. X got 56%, so Y got 44%. Step 2: X won by 56 − 44 = 12% of votes cast = 1440. So votes cast = 1440 ÷ 0.12 = 12000. Step 3: votes cast are 80% of the list. So the list = 12000 ÷ 0.8 = 15000. Option (b), 12000, is the votes cast, not the list. Options (c) and (d) are miscalculations.
Tip: the winning margin is the difference in percentages. Then work back step by step to the base you need.
12000 is the votes cast, not the voters list. It is the trap option.
Answer as per the official UPSC answer key.