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.
Read the passage
In India, the segregation of municipal waste at source is rare. Recycling is mostly with the informal sector. More than three-fourths of the municipal budget goes into collection and transportation, which leaves very little for processing/resource recovery and disposal. Where does waste-to-energy fit into all this ? Ideally it fits in the chain after segregation (between wet waste and the rest), collection, recycling, and before getting to the landfill. Which technology is most appropriate in converting waste to energy depends on what is in the waste (that is biodegradable versus non-biodegradable component) and its calorific value. The biodegradable component of India’s municipal solid waste is a little over 50 per cent, and biomethanation offers a major solution for processing this.
Which one of the following statements best reflects the crux of the passage ?
Answer (c) & explanation
The crux is that segregating waste is the first step to make waste-to-energy plants work (c). Step 1: the passage says waste-to-energy fits "after segregation". The right technology depends on what is in the waste. Step 2: but it opens by saying segregation at source "is rare" in India. So without segregation, these plants cannot succeed. That is (c). Step 3: option (b) calls biomethanation the most ideal way; the passage says only "a major solution". Option (a), cheap energy, is not claimed. Option (d) contradicts the "over 50 per cent" biodegradable share.
Tip: India's Solid Waste Management Rules, 2016 require segregation at source. Biomethanation turns wet waste into biogas.
Answer as per the official UPSC answer key.
Read the passage
India should ensure the growth of the digital economy while keeping personal data of citizens secure and protected. No one will innovate in a surveillance-oriented environment or in a place where an individual’s personal information is compromised. The ultimate control of data must reside with the individuals who generate it; they should be enabled to use, restrict or monetise it as they wish. Therefore, data protection laws should enable the right kind of innovation — one that is user-centric and privacy protecting.
Based on the above passage, the following assumptions have been made :
- 1. Protection of privacy is not just a right, but it has value to the economy.
- 2. There is a fundamental link between privacy and innovation.
Which of the above assumptions is/are valid ?
Answer (c) & explanation
Both assumptions are valid (c). Step 1: the passage says India should grow its digital economy while keeping personal data safe. So data protection has economic value, not just rights value (1). Step 2: it says "no one will innovate" where personal data is compromised. So privacy and innovation are closely linked (2). Step 3: so options (a), (b) and (d) fail.
Tip: India passed the Digital Personal Data Protection Act in 2023, and its rules were notified in November 2025. The Supreme Court declared privacy a fundamental right in the Puttaswamy case (2017).
Answer as per the official UPSC answer key.
Read the passage
The emissions humans put into the atmosphere now will affect the climate in the middle of the century and onwards. Technological change, meanwhile, could make a future transition away from fossil fuels cheap or it might not, leaving the world with a terrible choice between sharply reducing emissions at huge cost or suffering through the effects of unabated warming. Businesses that do not hedge against the threat of uncertain outcomes fail. The world cannot afford such recklessness on climate change.
Which one of the following statements best reflects the crucial message conveyed by the author of the passage ?
Answer (c) & explanation
The crucial message is that waiting for better technology before cutting emissions is unwise (c). Step 1: the passage says today's emissions will affect the climate from mid-century. Step 2: technology "could make a future transition cheap or it might not". Betting on it is reckless, like a business that fails to hedge. So act now. That is (c). Step 3: option (b) makes technology the only solution, the very gamble the author warns against. Option (a), closing businesses, and option (d), only renewable industries, are not argued.
Tip: when an author says "it might not", he is warning against relying on it. Pick the option that rejects waiting.
Answer as per the official UPSC answer key.
Read the passage
Along with sustainable lifestyles, climate justice is regarded as a significant principle in environmental parlance. Both the principles have bearings on political and economic choices of the nation. So far, in our climate change summits or compacts, both the principles have eluded consensus among nations. Justice, in the judicial sense, is well defined. However, in the context of climate change, it has scientific as well as socio-political connotations. The crucial question in the next few years will be how resources, technologies and regulations are used to support the victims of climate change. Justice in climate is not confined to actions relating to mitigation, but includes the wider notion of support for adaptation to climate change and compensation for loss and damage.
Which one of the following statements best reflects the most logical, rational and crucial message conveyed by the passage ?
Answer (a) & explanation
The crucial message is that climate justice should be built in detail into the rules of new climate agreements (a). Step 1: the passage says climate justice has "eluded consensus" in climate summits. Step 2: it says justice covers not just mitigation but also adaptation support and loss and damage. These need to be spelled out in agreements. That is (a). Step 3: option (b), uneven resources, and option (c), climate refugees, are not the main point. Option (d) blames developed countries, which the passage does not state.
Tip: a Loss and Damage Fund was agreed at COP27 (2022) and made operational at COP28 (2023). It is a step toward the climate justice this passage discusses.
Answer as per the official UPSC answer key.
Consider the sequence ABC_ _ABC_DABBCD_ABCD that follows a certain pattern. Which one of the following completes the sequence?
Answer (d) & explanation
The sequence is completed by DDCA (d). Step 1: put D, D, C, A into the gaps. The sequence becomes ABCDDABCCDABBCDAABCD. Step 2: split it into blocks of four: ABCD, DABC, CDAB, BCDA, ABCD. Step 3: each block moves the last letter to the front of the previous block. The pattern holds throughout, so (d). Options (a), (b) and (c) break it.
Tip: in letter-series gaps, try each option and split the result into equal blocks. A rotation pattern is very common.
Answer as per the official UPSC answer key.
Read the passage
Good corporate governance structures encourage companies to provide accountability and control. A fundamental reason why corporate governance has moved onto the economic and political agenda worldwide has been the rapid growth in international capital markets. Effective corporate governance enhances access to external financing by firms, leading to greater investment, higher growth and employment. Investors look to place their funds where the standards of disclosure, of timely and accurate financial reporting, and of equal treatment to all stakeholders are met.
Which of the following statements best reflects the logical inference from the passage given above ?
Answer (b) & explanation
The logical inference is that good corporate governance improves firms' credibility (b). Step 1: the passage says investors put their money where disclosure, accurate reporting and fair treatment are strong. So good governance builds trust. That is (b). Step 2: option (a) says external financing is the world's agenda. But the passage says corporate governance moved onto the agenda. Step 3: option (c) says capital markets ensure good governance; they only explain its rise. Option (d), supply chains, is not mentioned.
Tip: separate cause from result. Capital markets explain why governance became important; they do not guarantee it.
Answer as per the official UPSC answer key.
40 children are standing in a circle and one of them (say child-1) has a ring. The ring is passed clockwise. Child-1 passes on to child-2, child-2 passes on to child-4, child-4 passes on to child-7 and so on. After how many such changes (including child-1) will the ring be in the hands of child-1 again ?
Answer (b) & explanation
The ring returns after 15 changes (b). Step 1: the jumps grow by one each time: 1, 2, 3 and so on. After k passes, the ring has moved 1 + 2 + ... + k = k(k + 1)/2 places. Step 2: it is back with child-1 when this is a multiple of 40. So k(k + 1) must be a multiple of 80 = 16 × 5. Step 3: the smallest such k is 15, since 15 × 16 = 240 = 80 × 3. Options (a) 14, (c) 16 and (d) 17 do not give a multiple of 80 first.
Tip: in a circle of n, you return to the start when the total steps moved is a multiple of n.
Answer as per the official UPSC answer key.
Read the passage
We often hear about conflicts among different States in India over river waters. Of the 20 major river systems, 14 are already water-stressed; 75% of the population lives in water-stressed regions, a third of whom live in water-scarce areas. Climate change, the demands of rising population and the need for agriculture to keep pace, and increased rate of urbanization and industrialization will exacerbate water stress. According to the Constitution of India, water is a State subject and not that of the Union, except for regulation of inter-State rivers. Key to ensuring balance between competing demands of various stakeholders is a basin-based approach to allocate water amongst constituent regions and States. Allocating fair share of water to them requires assessments based on objective criteria, such as specificities of the river basin, size of dependent population, existing water use and demand, efficiency of use, projected future use, etc. while ensuring the environmental needs of the river and aquifers.
Which one of the following statements best reflects the most rational, practical and immediate action required to ensure fair and equitable allocation of water to different stakeholders ?
Answer (a) & explanation
The immediate action is a national, practical legal and policy framework for allocating water (a). Step 1: the passage says water is a State subject, and States often fight over rivers. Step 2: it says the key is a basin-based approach that shares water using objective criteria: basin features, population, current use, efficiency and future needs. That is a framework for allocation, so (a). Step 3: options (b) river linking and (c) new channels are engineering projects the passage never proposes. Option (d), cutting demand, is not the fair-allocation step it asks for.
Tip: under the Constitution, water is in the State List (Entry 17), while inter-State rivers fall under the Union (Entry 56). This is why fair-sharing rules matter.
Answer as per the official UPSC answer key.
Read the passage
There is a claim that organic farming is inherently safer and healthier. The reality is that because the organic farming industry is still young and not well-regulated in India, farmers and consumers, alike, are not only confused about what products are best for them, but sometimes use products in ways that could harm them as well. For example, since organic fertilizers are difficult to obtain on a large scale in India, farmers often use farmyard manure, which may contain toxic chemicals and heavy metals. Certain plant sprays, such as Datura flower and leaf spray, have an element called atropine. If it is not applied in the right dose, it can act on the nervous system of the consumer. Unfortunately, how much and when to use it are not well-researched or regulated issues.
Based on the above passage, the following assumptions have been made :
- 1. Organic farming is inherently unsafe for both farmers and consumers.
- 2. Farmers and consumers need to be educated about eco-friendly food.
Which of the assumptions given above is/are correct ?
Answer (b) & explanation
Only assumption 2 is correct (b). Step 1: the passage says farmers and consumers are confused about which products are best and sometimes use them in harmful ways. So both need to be educated (2). Step 2: it blames harm on poor regulation, contaminated farmyard manure and wrong doses of sprays like Datura. Step 3: it does not say organic farming is inherently unsafe (1). The problem is misuse, not organic farming itself. So options (a), (c) and (d) fail.
Tip: "inherently" means by its very nature. If the passage blames how something is used, it is not inherently bad.
Answer as per the official UPSC answer key.
In an examination, the maximum marks for each of the four papers namely P, Q, R and S are 100. Marks scored by the students are in integers. A student can score 99% in n different ways. What is the value of n ?
Answer (d) & explanation
1. 99% of 400 = 396, so the student loses exactly 4 marks in total across the four papers.
2. Count the ways to share the 4 lost marks:
3. All 4 in one paper: 4 ways. 3 + 1: 4 × 3 = 12 ways. 2 + 2: 6 ways. 2 + 1 + 1: 12 ways. 1 + 1 + 1 + 1: 1 way.
4. Total 4 + 12 + 6 + 12 + 1 = 35.
'no paper above 100' does not cut any case here, because a loss can't be negative.
Answer as per the official UPSC answer key.
Read the passage
Environmental problems cause health problems. Substantial changes in lifestyle can reduce environmental or health problems, but this idea appears almost impossible to adopt. With environmental problems, individual efforts can be perceived as having a negligible effect and therefore lead to inertia. With health, on the other hand, individual choices can make the difference between life and death, literally. And yet, barring a few, there seems to be the same collective lethargy towards making their choices.
Which one of the following statements best implies the most rational assumption that can be made from the passage ?
Answer (a) & explanation
The rational assumption is that we are likely to spend more on cure than prevention (a). Step 1: the passage says lifestyle changes could cut health problems. Step 2: but people show "collective lethargy" about making those choices, even when life and death are at stake. If they will not prevent illness, they will later pay for cure. That is (a). Step 3: option (c), health protected while environmental problems go on, goes against the first line. Options (b), government's job, and (d), western values, are not in the passage.
Tip: an assumption often follows from the passage's main complaint. Here the complaint is inaction on prevention.
Answer as per the official UPSC answer key.
A principal P becomes Q in 1 year when compounded half-yearly with R% annual rate of interest. If the same principal P becomes Q in 1 year when compounded annually with S% annual rate of interest, then which one of the following is correct ?
Answer (c) & explanation
R is less than S (c). Step 1: at the same rate, half-yearly compounding gives more than annual compounding, because interest earns interest sooner. Step 2: here both give the same amount Q. So the half-yearly rate R must be smaller. Step 3: exactly: (1 + R/200)² = 1 + S/100, which gives S = R + R²/400. So S is always more than R for any positive rate. Option (a) and (d) allow equality, which is impossible. Option (b) reverses it.
Tip: more frequent compounding needs a lower rate to reach the same amount. This is why banks quote both a nominal and an effective rate.
Answer as per the official UPSC answer key.
AB and CD are 2-digit numbers. Multiplying AB with CD results in a 3-digit number DEF. Adding DEF to another 3-digit number GHI results in 975. Further A, B, C, D, E, F, G, H, I are distinct digits. If E = 0, F = 8, then what is A + B + C equal to?
Answer (a) & explanation
A + B + C is 6 (a). Step 1: AB × CD = D08, a 3-digit number. So both AB and CD are small, and B × D must end in 8. Step 2: try 12 × 34 = 408. Here D = 4, E = 0 and F = 8. Then GHI = 975 − 408 = 567. Step 3: all nine digits (1, 2, 3, 4, 0, 8, 5, 6, 7) are distinct. So A + B + C = 1 + 2 + 3 = 6. Options (b), (c) and (d) do not fit.
Tip: in such puzzles, a small product means small factors. Start with the smallest two-digit numbers.
Answer as per the official UPSC answer key.
Read the passage
Elephants are landscape architects, creating clearings in the forest, preventing overgrowth of certain plant species and allowing space for the regeneration of others, which in turn provide sustenance to other herbivorous animals. Elephants eat plants, fruits and seeds, propagating the seeds when they defecate in other places as they travel. Elephant dung provides nourishment to plants and animals and acts as a breeding ground for insects. In times of drought, they access water by digging holes which benefits other wildlife.
Which one of the following statements best reflects the most logical and rational inference that can be drawn from the passage ?
Answer (b) & explanation
The best inference is that elephants are a keystone species that benefit biodiversity (b). Step 1: the passage says elephants make clearings, spread seeds through dung, feed insects and plants with dung, and dig waterholes in drought. Step 2: all these help many other species. A species whose role supports so many others is a keystone species. That is (b). Step 3: option (c) says biodiversity cannot survive without them, which is too absolute. Option (d) gives elephants a purpose, as if they plan the forest. Option (a) talks of home range, which is not discussed.
Tip: a keystone species has a large effect on its ecosystem relative to its numbers. India declared the elephant its National Heritage Animal in 2010.
Answer as per the official UPSC answer key.
What is the middle term of the sequence
Z, Z, Y, Y, Y, X, X, X, X, W, W, W, W, W, …, A ?
Answer (b) & explanation
The middle term is I (b). Step 1: Z appears 2 times, Y 3 times, X 4 times, and so on. The kth letter from Z appears k + 1 times, so A appears 27 times. Step 2: total terms = 2 + 3 + ... + 27 = 377. The middle term is the 189th. Step 3: the first m letters fill m(m + 3)/2 places. For m = 18 this is exactly 189. The 18th letter counting back from Z is I. Options (a) H, (c) J and (d) M are off.
Tip: counting back from Z, letter number k is the letter at position 27 − k. Here 27 − 18 = 9, which is I.
Answer as per the official UPSC answer key.
Read the passage
More than half of Indian women and almost a quarter of Indian men of working age suffer from anaemia. According to studies, they are anywhere from 5–15% less productive than they could be, as a result thereof. India also has the largest tuberculosis burden in the world, costing 170 million workdays to the country annually. But what is just as important as lost productivity now is lost potential in the future. It is becoming increasingly clear that on many measures of cognitive ability, malnourished Indian children perform two or three times worse than their adequately nourished peers. For an economy that will be more dependent on highly skilled workers, this poses a significant challenge. And it is one that really should be addressed given India’s demographic outlook.
Which one of the following statements best reflects what is implied by the passage ?
Answer (d) & explanation
The implication is that for rapid growth, attention must go to people's health and nutrition (d). Step 1: the passage says anaemia makes workers 5–15% less productive, and TB costs 170 million workdays a year. Step 2: it adds that malnourished children do two or three times worse on cognitive tests, hurting future potential. So health and nutrition drive growth. That is (d). Step 3: option (c) says only skilled workers need attention, which is too narrow. Options (a) and (b) shift to education and skills, which the passage does not discuss.
Tip: the passage links health to productivity both now and in future. Pick the option that covers all the people, not one group.
Answer as per the official UPSC answer key.
Read the passage
There is a claim that organic farming is inherently safer and healthier. The reality is that because the organic farming industry is still young and not well-regulated in India, farmers and consumers, alike, are not only confused about what products are best for them, but sometimes use products in ways that could harm them as well. For example, since organic fertilizers are difficult to obtain on a large scale in India, farmers often use farmyard manure, which may contain toxic chemicals and heavy metals. Certain plant sprays, such as Datura flower and leaf spray, have an element called atropine. If it is not applied in the right dose, it can act on the nervous system of the consumer. Unfortunately, how much and when to use it are not well-researched or regulated issues.
Which one of the following statements best reflects the most logical, rational and practical message conveyed by the author of the passage ?
Answer (c) & explanation
The message is that Indian farmers need guidance and help to make organic farming sustainable (c). Step 1: the passage says the organic industry is "young and not well-regulated". Step 2: doses and timing of sprays are "not well-researched or regulated". So farmers need guidance. That is (c). Step 3: option (a) says organic farming should not be promoted, and option (b) says there are no safe alternatives. Both reject organic farming, which the author does not do. Option (d), profits and global markets, is not discussed.
Tip: a critical passage is not always against the idea. Here the author wants organic farming done right, not stopped.
Answer as per the official UPSC answer key.
A flag has to be designed with 4 horizontal stripes using some or all of the colours red, green and yellow. What is the number of different ways in which this can be done so that no two adjacent stripes have the same colour ?
Answer (c) & explanation
There are 24 ways (c). Step 1: the top stripe can be any of 3 colours. Step 2: each stripe below only has to differ from the one above it, so it has 2 choices. Step 3: 3 × 2 × 2 × 2 = 24. "Some or all" colours means using just two colours (like red-green-red-green) is allowed. Option (d), 36, and the others miscount.
Tip: for "no two adjacent the same", the first item has n choices and each next one has n − 1.
Answer as per the official UPSC answer key.
Read the passage
Many people are not eating the right food. For some, it is simply a decision to stick with food they enjoy but which is not too healthy. This is leading to an increase in non-communicable diseases. This in turn leads to major burden on our health-care systems that have the potential to derail the economic progress which is essential for the poor to improve their lives. For others, it is about limited access to nutritious food or a lack of affordability, leading to monotonous diets that do not provide the daily nutrients for them to develop fully. Part of the reason nutrition is under threat worldwide is that our food systems are not properly responding to nutritional needs. Somewhere along that long road from farm to fork, there are serious detours taking place.
Which one of the following statements best reflects the crux of the passage ?
Answer (b) & explanation
The crux is that food-based nutrition must be at the centre of policy debate (b). Step 1: the passage says many people eat unhealthy food, which raises non-communicable diseases. Others lack access to nutritious food. Step 2: it says our food systems are not responding to nutritional needs, with "detours" from farm to fork. So nutrition must come first in food policy. That is (b). Step 3: option (a), Universal Basic Income, is not mentioned. Options (c) GM crops and (d) food fortification are specific fixes the passage does not propose.
Tip: the crux is the broad idea the passage builds to. Options naming specific technologies are usually too narrow.
Answer as per the official UPSC answer key.
How many natural numbers are there which give a remainder of 31 when 1186 is divided by these natural numbers ?
Answer (d) & explanation
There are 9 such numbers (d). Step 1: if 1186 leaves remainder 31, then the divisor n divides 1186 − 31 = 1155. Also, n must be greater than 31 (a remainder is always smaller than the divisor). Step 2: 1155 = 3 × 5 × 7 × 11, which has 2 × 2 × 2 × 2 = 16 divisors. Step 3: those above 31 are 33, 35, 55, 77, 105, 165, 231, 385 and 1155. That is 9. Options (a), (b) and (c) miss some.
Tip: never forget the rule that the divisor must exceed the remainder. It removes the small divisors.
a remainder of 31 needs a divisor larger than 31. Counting all 16 divisors is the trap.
Answer as per the official UPSC answer key.