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 a school, 60% students play cricket. A student who does not play cricket, plays football. Every football player has got a two-wheeler. Which of the following conclusions cannot be drawn from the above data ?
- 1. 60% of the students do not have two-wheelers.
- 2. No cricketer has a two-wheeler.
- 3. Cricket players do not play football.
Select the correct answer using the code given below :
Answer (d) & explanation
None of the three conclusions can be drawn, so the answer is 1, 2 and 3 (d). Step 1: we know the 40% who do not play cricket play football, and every football player has a two-wheeler. Step 2: about cricketers we know nothing more. A cricketer may also play football, and may or may not own a two-wheeler. Step 3: so 1 (60% have no two-wheelers), 2 (no cricketer has one) and 3 (cricketers do not play football) are all unproven. Options (a), (b) and (c) fail.
Tip: "A student who does not play cricket plays football" does not mean cricketers never play football. A one-way rule cannot be reversed.
the question asks what cannot be drawn. Read 'cannot' twice.
UPSC repeats traps like this year after year. The PYQ Book gathers every trap in one place, so you see them coming. Try the free sample
Answer as per the official UPSC answer key.
Read the passage
In a study, scientists compared the microbiomes of poorly nourished and well nourished infants and young children. Gut microbes were isolated from faecal samples of malnourished and healthy children. The microbiome was “immature” and less diverse in malnourished children compared to the better developed “mature” microbiome found in healthy children of the same age. According to some studies, the chemical composition of mother’s milk has shown the presence of a modified sugar (sialylated oligosaccharides). This is not utilized by the baby for its own nutrition. However, the bacteria constituting the infant’s microbiome thrive on this sugar which serves as their food. Malnourished mothers have low levels of this sugar in their milk. Consequently, the microbiomes of their infants fail to mature. That in turn, leads to malnourished babies.
On the basis of the above passage, the following assumptions have been made :
- 1. Processed probiotic foods are a solution to treat the children suffering from malnutrition due to immature gut bacteria composition.
- 2. The babies of malnourished mothers generally tend to be malnourished.
Which of the above assumptions is/are valid ?
Answer (b) & explanation
Only assumption 2 is valid (b). Step 1: the passage says malnourished mothers' milk has less of certain sugars. This keeps their babies' gut bacteria immature, which "leads to malnourished babies". So babies of malnourished mothers tend to be malnourished. Assumption 2 holds. Step 2: assumption 1 offers processed probiotic foods as a cure. Probiotic foods are not mentioned in the passage. Step 3: so options (a), (c) and (d) fail.
Tip: this is part of the cycle of malnutrition: an underfed mother often has an underweight baby. India's POSHAN Abhiyaan targets mothers and young children together for this reason.
Answer as per the official UPSC answer key.
A and B are two heavy steel blocks. If B is placed on the top of A, the weight increases by 60%. How much weight will reduce with respect to the total weight of A and B, if B is removed from the top of A?
Answer (d) & explanation
The weight falls by 37·5% (d). Step 1: take A = 100 for ease. Putting B on top raises the weight by 60%, so B = 60 and the total = 160. Step 2: removing B takes off 60. Step 3: as a share of the total of 160: 60 ÷ 160 = 3/8 = 37·5%. Option (a), 60%, uses A as the base instead of the total. Options (b) and (c) are also wrong.
Tip: the base changes everything. A rise of 60% on 100 is a fall of 37·5% on 160. To reverse an increase of x%, the fall is x ÷ (100 + x) × 100. Here 60 ÷ 160 × 100 = 37·5%. Choosing 100 as the starting value makes such sums easy.
the base changes: 60% of A is not 60% of (A + B).
One trap spotted is one mark saved. The PYQ Book lines up every trap UPSC has set, so you walk in prepared. Try the free sample
Answer as per the official UPSC answer key.
Read the passage
Most invasive species are neither terribly successful nor very harmful. Britain’s invasive plants are not widespread, not spreading especially quickly, and often less of a nuisance than vigorous natives such as bracken. The arrival of new species almost always increases biological diversity in a region; in many cases, a flood of newcomers drives no native species to extinction. One reason is that invaders tend to colonise disturbed habitats like polluted lakes and post-industrial wasteland, where little else lives. They are nature’s opportunists.
Which one of the following is the most logical and rational inference that can be made from the above passage ?
Answer (c) & explanation
The inference is that campaigns against foreign plants are sometimes pointless (c). Step 1: the passage says most invading plants are "neither terribly successful nor very harmful". So fighting all of them can be a waste. "Sometimes" matches this. That is (c). Step 2: option (b) calls laws unnecessary. But "most" means some invaders are harmful, so some laws are needed. Step 3: options (a) and (d) ask us to deliberately use foreign plants for deserts or biodiversity. The passage never recommends this.
Tip: "most" supports "sometimes", but not "always" or "never". India's Lantana and Parthenium (congress grass) show that a few invaders do great harm.
Answer as per the official UPSC answer key.
An 8-digit number 4252746B leaves remainder 0 when divided by 3. How many values of B are possible?
Answer (c) & explanation
B can take 4 values (c). Step 1: a number is divisible by 3 if the sum of its digits is divisible by 3. Step 2: digits without B: 4 + 2 + 5 + 2 + 7 + 4 + 6 = 30. That is already a multiple of 3. Step 3: so B itself must be a multiple of 3: 0, 3, 6 or 9. That is 4 values. Option (b), 3, forgets 0. Options (a) and (d) miscount.
Tip: remember divisibility rules: by 3 or 9, use the digit sum; by 4, the last two digits; by 8, the last three; by 11, the difference of alternate digit sums. And 0 is a valid digit, so do not skip it.
don't forget B = 0.
Answer as per the official UPSC answer key.
Read the passage
With the digital phenomenon restructuring most social sectors, it is little surprise that global trade negotiations are now eyeing the digital area in an attempt to pre-emptively colonise it. Big Data is freely collected or mined from developing countries, and converted into digital intelligence in developed countries. This intelligence begins to control different sectors and extract monopoly rents. A large foreign company providing cab service, for instance, is not a network of cars and drivers; it is digital intelligence about commuting, public transport, roads, traffic, city events, personal behavioural characteristics of commuters and drivers and so on.
Which one of the following is the most logical and rational corollary to the above passage ?
Answer (b) & explanation
The corollary is that India should protect its digital sovereignty in trade talks (b). Step 1: the passage says global trade talks try to "pre-emptively colonise" the digital space, using data from developing countries. So a developing country like India must guard its data. That is (b). Step 2: option (a) condemns all globalization, which goes far beyond the passage. Step 3: option (c), charging monopoly rents, reverses the passage, which blames big firms for earning such rents. Option (d) invents a proportional link to foreign trade.
Tip: a corollary is a natural next step from the passage. Choose the option that follows directly, not one that condemns a whole system.
Answer as per the official UPSC answer key.
Consider the following sequence that follows some arrangement :
c_accaa_aa_bc_b
The letters that appear in the gaps are
Answer (b) & explanation
The letters in the gaps are c, b, b, b (b). Step 1: split the series into blocks of five: c_acc | aa_aa | _bc_b. Step 2: each block has the pattern XXYXX: two of one letter, one different letter, then two of the first. Filling in: ccacc, aabaa, bbcbb. Step 3: the gaps, in order, are c, b, b, b. That is option (b). Options (a), (c) and (d) break the XXYXX pattern.
Tip: in letter series, count the total letters and try splitting them into equal blocks (of 4, 5 or 6). A repeating block usually becomes clear at once.
Answer as per the official UPSC answer key.
Read the passage
Political theorists no doubt have to take history of injustice, for example, untouchability, seriously. The concept of historical injustice takes note of a variety of historical wrongs that continue into the present in some form or the other and tend to resist repair. Two reasons might account for resistance to repair. One, not only are the roots of injustice buried deep in history, injustice itself constitutes economic structures of exploitation, ideologies of discrimination and modes of representation. Two, the category of historical injustice generally extends across a number of wrongs such as economic deprivation, social discrimination and lack of recognition. This category is complex, not only because of the overlap between a number of wrongs, but because one or the other wrong, generally discrimination, tends to acquire partial autonomy from others. This is borne out by the history of repair in India.
What is the main idea that we can infer from the passage ?
Answer (d) & explanation
The main idea is that it is hard, if not impossible, to repair every form of historical injustice (d). Step 1: the passage says historical wrongs "tend to resist repair" because they are deep-rooted and overlap with one another. That matches (d). Step 2: option (b) says injustice is inevitable and always beyond repair. "Tend to resist" is softer than "always", so (b) overstates. Step 3: option (a) fails because the passage says theorists "have to take" untouchability seriously; it does not say they ignored it. Option (c) blames bad economies, which the passage never says.
Tip: match the strength of the option to the passage. "Tend to" fits "difficult", not "always" or "never".
Answer as per the official UPSC answer key.
The ratio of a two-digit natural number to a number formed by reversing its digits is 4 : 7. The number of such pairs is
Answer (b) & explanation
There are 4 such pairs (b). Step 1: let the number be 10a + b; reversed, it is 10b + a. Given (10a + b) : (10b + a) = 4 : 7, so 7(10a + b) = 4(10b + a). Step 2: 70a + 7b = 40b + 4a, so 66a = 33b, which gives b = 2a. Step 3: b must be a single digit, so a can be 1, 2, 3 or 4. The numbers are 12, 24, 36 and 48 (12 : 21 = 4 : 7, and so on). a = 5 would give b = 10, which is not a digit. Options (a), (c) and (d) fail.
Tip: write a two-digit number as 10a + b. Always check that the digits stay between 0 and 9.
Answer as per the official UPSC answer key.
Read the passage
Temperatures have risen nearly five times as rapidly on the Western Antarctic Peninsula than the global average over the past five decades. Researchers have now found that melting glaciers are causing a loss of species diversity among benthos in the coastal waters off the Antarctic Peninsula, impacting an entire seafloor ecosystem. They believe increased levels of suspended sediment in water to be the cause of the dwindling biodiversity in the coastal region.
On the basis of the above passage, the following assumptions have been made :
- 1. Regions of glaciers warm faster than other regions due to global warming.
- 2. Global warming can lead to seafloor sedimentation in some areas.
- 3. Melting glaciers can reduce marine biodiversity in some areas.
Which of the above assumptions is/are valid ?
Answer (c) & explanation
Assumptions 2 and 3 are valid (c). Step 1: the passage says warming melts glaciers, which raises the amount of suspended sediment in the sea. So warming can cause seafloor sedimentation in some areas (2). Step 2: it says this sediment cuts the diversity of benthic (seafloor) life. So melting glaciers can reduce marine biodiversity (3). Step 3: assumption 1 says all glacier regions warm faster than others. The passage speaks of one peninsula warming fast. One case does not prove a general rule. So options (a), (b) and (d) fail.
Tip: "in some areas" makes 2 and 3 safe. A single example cannot support a claim about every region.
Answer as per the official UPSC answer key.
Mr 'X' has three children. The birthday of the first child falls on the 5th Monday of April, that of the second one falls on the 5th Thursday of November. On which day is the birthday of his third child, which falls on 20th December?
Answer (b) & explanation
1. April has 30 days. A 5th Monday needs Monday on 29 or 30 April, so 1 April is a Monday or a Sunday.
2. 1 April to 1 November = 214 days = 30 weeks + 4 days. So 1 November is Friday or Thursday. A 5th Thursday in November (30 days) needs 1 November to be Wednesday or Thursday, so 1 November = Thursday.
3. 20 December is 49 days later = exactly 7 weeks. Thursday.
Answer as per the official UPSC answer key.
Read the passage
Diarrhoeal deaths among Indian children are mostly due to food and water contamination. Use of contaminated groundwater and unsafe chemicals in agriculture, poor hygiene in storage and handling of food items to food cooked and distributed in unhygienic surroundings; there are myriad factors that need regulation and monitoring. People need to have awareness of adulteration and ways of complaining to the relevant authorities. Surveillance of food-borne diseases involves a number of government agencies and entails a good training of inspection staff. Considering the proportion of the urban population that depends on street food for its daily meals, investing in training and education of street vendors is of great significance.
On the basis of the above passage, the following assumptions have been made :
- 1. Food safety is a complex issue that calls for a multipronged solution.
- 2. Great investments need to be made in developing the manpower for surveillance and training.
- 3. India needs to make sufficient legislation for governing food processing industry.
Which of the above assumptions is/are valid ?
Answer (a) & explanation
Assumptions 1 and 2 are valid (a). Step 1: the passage says "myriad factors" affect food safety and call for regulation, awareness and surveillance. So it is a complex issue needing many fixes. Assumption 1 holds. Step 2: it says food inspectors and vendors need training. So investment in manpower for surveillance and training is needed. Assumption 2 holds. Step 3: assumption 3 is about laws for the food processing industry. That industry is not discussed. So 3 fails, and options (b), (c) and (d) fail.
Tip: India's food regulator is FSSAI, set up under the Food Safety and Standards Act, 2006. But in CSAT, use only what the passage says.
Answer as per the official UPSC answer key.
Six students A, B, C, D, E and F appeared in several tests. Either C or F scores the highest. Whenever C scores the highest, then E scores the least. Whenever F scores the highest, B scores the least. In all the tests they got different marks; D scores higher than A, but they are close competitors; A scores higher than B; C scores higher than A.
If F stands second in the ranking, then the position of B is
Answer (c) & explanation
B is fifth (c). Step 1: F is second, so F is not first. So C is first. When C is first, E is last (sixth). Step 2: the remaining places 3, 4 and 5 go to D, A and B. We know D > A and A > B. Step 3: so D is 3rd, A is 4th and B is 5th. Option (d), sixth, belongs to E. Options (a) and (b) break D > A > B.
Tip: in ranking puzzles, apply the "if" condition first, then the fixed rules ("whenever C is highest, E is least"). Fill the remaining spots using the chain of comparisons.
Answer as per the official UPSC answer key.
Read the passage
With the digital phenomenon restructuring most social sectors, it is little surprise that global trade negotiations are now eyeing the digital area in an attempt to pre-emptively colonise it. Big Data is freely collected or mined from developing countries, and converted into digital intelligence in developed countries. This intelligence begins to control different sectors and extract monopoly rents. A large foreign company providing cab service, for instance, is not a network of cars and drivers; it is digital intelligence about commuting, public transport, roads, traffic, city events, personal behavioural characteristics of commuters and drivers and so on.
Which of the following is most definitively implied by the above passage ?
Answer (a) & explanation
The passage most clearly implies that Big Data is the key resource in the digital space (a). Step 1: it says data turned into "digital intelligence" lets firms control whole sectors and earn monopoly rents. So data is the central resource. That is (a). Step 2: option (b) says big economies create Big Data. But the passage says much data comes from developing countries, which weakens (b). Step 3: options (c) and (d) say Big Data belongs to developed countries. The passage says rich-country firms grab it, not that access is their right or nature.
Tip: data is often called "the new oil". India's Digital Personal Data Protection Act, 2023 is one response to this concern.
Answer as per the official UPSC answer key.
A family has two children along with their parents. The average of the weights of the children and their mother is 50 kg. The average of the weights of the children and their father is 52 kg. If the weight of the father is 60 kg, then what is the weight of the mother?
Answer (d) & explanation
The mother weighs 54 kg (d). Step 1: the average of the two children and the mother is 50, so their total = 150 kg. The average of the children and the father is 52, so that total = 156 kg. Step 2: both totals include the same two children. So the difference, 156 − 150 = 6 kg, is the father's weight minus the mother's. Step 3: mother = 60 − 6 = 54 kg. Option (b), 50 kg, is just the first average. Options (a) and (c) do not fit.
Tip: when two groups share members, subtract their totals. The shared part cancels, leaving only the difference you need. You never have to find the children's weights.
Answer as per the official UPSC answer key.
Read the passage
Political theorists no doubt have to take history of injustice, for example, untouchability, seriously. The concept of historical injustice takes note of a variety of historical wrongs that continue into the present in some form or the other and tend to resist repair. Two reasons might account for resistance to repair. One, not only are the roots of injustice buried deep in history, injustice itself constitutes economic structures of exploitation, ideologies of discrimination and modes of representation. Two, the category of historical injustice generally extends across a number of wrongs such as economic deprivation, social discrimination and lack of recognition. This category is complex, not only because of the overlap between a number of wrongs, but because one or the other wrong, generally discrimination, tends to acquire partial autonomy from others. This is borne out by the history of repair in India.
On the basis of the above passage, the following assumptions have been made :
- 1. Removal of economic discrimination leads to removal of social discrimination.
- 2. Democratic polity is the best way to repair historical wrongs.
Which of the above assumptions is/are valid ?
Answer (d) & explanation
Neither assumption is valid (d). Step 1: the passage says discrimination gains "partial autonomy" from other wrongs. That means it can live on by itself. So removing economic discrimination need not remove social discrimination. Assumption 1 fails. Step 2: assumption 2 calls democracy the best way to repair historical wrongs. The passage never mentions democracy. So 2 fails. Step 3: so options (a), (b) and (c) fail.
Tip: "partial autonomy" is a key phrase: it means one problem does not simply depend on another. When an option brings in a new idea, like democracy, that the passage never raised, it cannot be a valid assumption.
Answer as per the official UPSC answer key.
In an examination, A has scored 20 marks more than B. If B has scored 5% less marks than A, how much has B scored?
Answer (b) & explanation
B scored 380 marks (b). Step 1: B scored 5% less than A. The gap of 20 marks is 5% of A's marks. Step 2: so A = 20 ÷ 0·05 = 400. Step 3: B = 400 − 20 = 380. Check: 5% of 400 is 20. It works. Option (c), 400, is A's score. Option (a), 360, subtracts twice. Option (d) does not fit.
Tip: "5% less than A" means the base is A. So the difference equals 5% of A. Finding A first is the key step. A quick check of each option against both facts also works: only 380 and 400 differ by 20 with a 5% gap based on the larger number.
400 is A's score, not B's.
Answer as per the official UPSC answer key.
Read the passage
A research team examined a long-term owl roost. Owls prey on small mammals and the excreted remains of those meals that accumulated over the time, provide us an insight into the composition and structure of small mammals over the past millennia. The research suggested that when the Earth went through a period of rapid warming about 13,000 years ago, the small mammal community was stable and resilient. But, from the last quarter of the nineteenth century, human-made changes to the environment had caused an enormous drop in biomass and energy flow. This dramatic decline in energy flow means modern ecosystems are not adapting as easily as they did in the past.
On the basis of the above passage, the following assumptions have been made :
- 1. Global warming is a frequently occurring natural phenomenon.
- 2. The impending global warming will not adversely affect small mammals.
- 3. Humans are responsible for the loss of the Earth’s natural resilience.
Which of the above assumptions is/are valid ?
Answer (b) & explanation
Only assumption 3 is valid (b). Step 1: the passage says human-made changes caused "an enormous drop in biomass and energy flow". So ecosystems now recover less easily. Humans have weakened Earth's natural resilience. Assumption 3 holds. Step 2: assumption 1 calls warming a frequent natural event. The passage describes one past warming episode, not frequent ones. So 1 fails. Step 3: assumption 2 says coming warming will not harm small mammals. Even if small mammals coped in the past, today's ecosystems are weaker. So 2 fails. Options (a), (c) and (d) fail.
Tip: a past event does not guarantee the same result today, especially when the passage says conditions have changed.
Answer as per the official UPSC answer key.
Consider the following Statements and Conclusions :
Statements :
- 1. Some rats are cats.
- 2. Some cats are dogs.
- 3. No dog is a cow.
Conclusions :
- I. No cow is a cat.
- II. No dog is a rat.
- III. Some cats are rats.
Which of the above conclusions is/are drawn from the statements ?
Answer (c) & explanation
Only conclusion III follows (c). Step 1: "Some rats are cats" can be turned round: some cats are rats. So III is true. Step 2: conclusion I says no cow is a cat. The cats that are dogs cannot be cows, but other cats may still be cows. Nothing rules this out, so I fails. Step 3: conclusion II says no dog is a rat. Nothing links dogs and rats either way, so II fails. Options (a), (b) and (d) fail.
Tip: "some A are B" always means "some B are A". But "some" statements cannot give "no" conclusions. Drawing quick circles (Venn diagrams) shows what must be true and what only may be true.
Answer as per the official UPSC answer key.
Read the passage
The interests of working and poor people have historically been neglected in the planning of our cities. Our cities are increasingly intolerant, unsafe and unlivable places for large numbers of citizens and yet we continue to plan via the old ways — the static Development Plan — that draws exclusively from technical expertise, distanced from people’s live experiences and needs, and actively excluding large number of people, places, activities and practices that are an integral part of the city.
The passage seems to argue
Answer (d) & explanation
The passage argues for people's groups taking part in city planning (d). Step 1: it says the flaw is planning "exclusively from technical expertise, distanced from people's lived experiences". The fix is to involve people. That is (d). Step 2: option (c) wants cities planned mainly for the poor. That would just swap one exclusion for another; the passage wants everyone included. Step 3: option (a), against builders and elites, and option (b), against smart cities, are not the passage's argument; it does not oppose these outright.
Tip: when a passage names a flaw ("exclusively experts"), the answer is the opposite: inclusion. India's 74th Amendment (1992) set up ward committees to give citizens a say.
Answer as per the official UPSC answer key.