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.)
Who is the artist ?
Answer (c) & explanation
R is the artist (c). Step 1: P and S are students, so the three jobs belong to Q, R and T. Step 2: Q is neither the doctor nor the artist, so Q is the lawyer. Step 3: R is not the doctor. The only job left for R is artist, and T is the doctor. So option (c) is right. Option (a) P is a student and has no job. Option (b) Q is the lawyer. Option (d) T is the doctor.
Tip: linked questions share one grid. Solve the grid fully once, then answer every question from it. This saves time and avoids answering the same puzzle in different ways.
Answer as per the official UPSC answer key.
Read the passage
About 15 per cent of global greenhouse gas emissions come from agricultural practices. This includes nitrous oxide from fertilizers; methane from livestock, rice production, and manure storage; and carbon dioxide (CO₂) from burning biomass, but this excludes CO₂ emissions from soil management practices, savannah burning and deforestation. Forestry, land use, and land-use change account for another 17 per cent of greenhouse gas emissions each year, three quarters of which come from tropical deforestation. The remainder is largely from draining and burning tropical peatland. About the same amount of carbon is stored in the world’s peatlands as is stored in the Amazon rainforest.
Which among the following is the most logical and rational inference that can be made from the above passage ?
Answer (b) & explanation
We must change our land use practices to fight climate change (b). Step 1: the passage says agriculture causes about 15% and land use change about 17% of greenhouse gas emissions. Together that is about a third. Step 2: so changing how we use land is a must, which is option (b). Step 3: option (a) wants organic farming "immediately… all over the world", which is far too extreme. Option (c), that there are no technical fixes, is not discussed. Option (d), that tropics are the main carbon store, is not stated.
Tip: agriculture and land use are big emission sources because of fertilisers, livestock and forest clearing. That is why climate plans stress forests and farming.
Answer as per the official UPSC answer key.
A person allows a 10% discount for cash payment from the marked price of a toy and still he makes a 10% gain. What is the cost price of the toy which is marked Rs. 770?
Answer (c) & explanation
The cost price is Rs 630 (c). Step 1: the marked price is Rs 770. A 10% discount gives a selling price of 90% of 770 = Rs 693. Step 2: he still makes a 10% profit, so 693 is 110% of the cost price. Step 3: cost price = 693 ÷ 1.1 = Rs 630. Check: 630 + 10% = 693. Option (a), Rs 610, and options (b) and (d) do not fit. A common mistake is to think a 10% discount and a 10% gain cancel out, giving 770.
Tip: discount is always on the marked price, and profit is always on the cost price. Keep the two bases separate.
Answer as per the official UPSC answer key.
Four friends A, B, C and D need to cross a bridge. A maximum of two persons can cross it at a time. It is night and they just have one lamp. Persons that cross the bridge must carry the lamp to find the way. A pair must walk together at the speed of slower person. After crossing the bridge, the person having faster speed in the pair will return with the lamp each time to accompany another person in the group. Finally, the lamp has to be returned at the original place and the person who returns the lamp has to cross the bridge again without lamp. To cross the bridge, the time taken by them is as follows : A: 1 minute, B: 2 minutes, C: 7 minutes and D: 10 minutes. What is the total minimum time required by all the friends to cross the bridge ?
Answer (a) & explanation
The minimum time is 23 minutes (a). Step 1: the rule says the faster person of each pair brings the lamp back. So A, the fastest (1 minute), should walk with everyone. Step 2: A + D cross (10), A returns (1), A + C cross (7), A returns (1), A + B cross (2). That is 21 minutes, and all four are across. Step 3: the puzzle adds that the lamp must be returned to the start, and the person who returns it must cross again without the lamp. A returns (1) and crosses back (1): 21 + 2 = 23 minutes. Option (c), 21, forgets this last rule. Options (b) and (d) do not follow the rules.
Tip: read every rule to the end; the last line often changes the answer.
the usual 17-minute trick (C and D crossing together) is not allowed here, because the faster person must return each time.
Answer as per the official UPSC answer key.
A cube has all its faces painted with different colours. It is cut into smaller cubes of equal sizes such that the side of the small cube is one-fourth the big cube. The number of small cubes with only one of the sides painted is :
Answer (b) & explanation
24 small cubes have only one face painted (b). Step 1: each side is cut into 4, so the big cube becomes 4 × 4 × 4 = 64 small cubes. Step 2: on each face there are 4 × 4 = 16 small cubes. The ones on the edges of that face also touch another face. Only the inner 2 × 2 = 4 have just one painted side. Step 3: a cube has 6 faces, so 6 × 4 = 24. Option (a), 32, does not fit. Option (d), 8, is the number of corner cubes, which have three painted faces.
Tip: for a cube cut n × n × n, one-face cubes = 6 × (n − 2)². Corner cubes are always 8.
Answer as per the official UPSC answer key.
Read the passage
In general, religious traditions stress our duty to god, or to some universal ethical principle. Our duties to one another derive from these. The religious concept of rights is primarily derived from our relationship to this divinity or principle and the implication it has on our other relationships. This correspondence between rights and duties is critical to any further understanding of justice. But, for justice to be practiced; virtue, rights and duties cannot remain formal abstractions. They must be grounded in a community (common unity) bound together by a sense of common union (communion). Even as a personal virtue, this solidarity is essential to the practice and understanding of justice.
Which one of the following is the crux of this passage ?
Answer (c) & explanation
The crux is that a balance between rights and duties is crucial to justice (c). Step 1: the key line is: "This correspondence between rights and duties is critical to any further understanding of justice." The whole passage builds towards this point. Step 2: option (a), that duties come from religious traditions, is an opening detail, not the main point. Option (d), that rights come from our relationship to god, is also a detail. Step 3: option (b), calling a relationship to the divine a great virtue, is a value judgement the passage never makes.
Tip: the crux is the idea the other sentences support. Supporting details from the start of a passage are common trap options.
Answer as per the official UPSC answer key.
A daily train is to be introduced between station A and station B starting from each end at 6 AM and the journey is to be completed in 42 hours. What is the number of trains needed in order to maintain the shuttle service ?
Answer (c) & explanation
1. Day 1, 6 AM: one train leaves A and one leaves B. That is 2 trains.
2. 42 hours = 1 day and 18 hours, so these trains arrive at midnight at the end of Day 2. On Day 2 at 6 AM they are still running, so 2 more trains are needed.
3. Day 3, 6 AM: the Day 1 trains have arrived and can go back. No new train is needed after this.
4. Total = 4 trains.
Answer as per the official UPSC answer key.
Read the passage
Historically, the biggest challenge to world agriculture has been to achieve a balance between demand for and supply of food. At the level of individual countries, the demand-supply balance can be a critical policy issue for a closed economy, especially if it is a populous economy and its domestic agriculture is not growing sufficiently enough to ensure food supplies, on an enduring basis; it is not so much and not always, of a constraint for an open, and growing economy, which has adequate exchange surpluses to buy food abroad. For the world as a whole, supply-demand balance is always an inescapable prerequisite for warding off hunger and starvation. However, global availability of adequate supply does not necessarily mean that food would automatically move from countries of surplus to countries of deficit if the latter lack in purchasing power. The uneven distribution of hunger, starvation, under- or malnourishment, etc., at the world-level, thus owes itself to the presence of empty-pocket hungry mouths, overwhelmingly confined to the underdeveloped economies. Inasmuch as ‘a two-square meal’ is of elemental significance to basic human existence, the issue of worldwide supply of food has been gaining significance, in recent times; both because the quantum and the composition of demand has been undergoing big changes, and because, in recent years, the capabilities of individual countries to generate uninterrupted chain of food supplies have come under strain. Food production, marketing and prices, especially price-affordability by the poor in the developing world, have become global issues that need global thinking and global solutions.
According to the above passage, which of the following helps/help in reducing hunger and starvation in the developing economies ?
- 1. Balancing demand and supply of food
- 2. Increasing imports of food
- 3. Increasing purchasing power of the poor
- 4. Changing the food consumption patterns and practices
Select the correct answer using the code given below :
Answer (c) & explanation
Statements 1 and 3 help reduce hunger (c). Step 1: the passage calls the balance of food demand and supply an "inescapable prerequisite". So statement 1 helps. Step 2: it says hunger comes from "empty-pocket hungry mouths". People are hungry because they cannot buy food. So raising the poor's purchasing power (3) helps. Step 3: increasing imports (2) needs money, so imports alone do not reach the poor. Changing food habits (4) is not suggested. So options (a), (b) and (d) fail.
Tip: this echoes Amartya Sen's idea of entitlement. Famines often happen not from a lack of food, but because the poor lack the income to buy it.
Answer as per the official UPSC answer key.
(Same information as the question above.)
Who is the spouse of R ?
Answer (b) & explanation
R's spouse is T (b). Step 1: T is a man married to someone in the group. Step 2: P and S are unmarried students, so they cannot be T's spouse. Q is the brother of P, so Q is a man, and here the married couple is taken as a man and a woman. Step 3: that leaves R as T's wife. So R's spouse is T. Option (a) P and option (d) S are unmarried. Option (c) Q is a man and P's brother, so he is not the spouse.
Tip: relation clues like "brother" also tell you a person's gender. Note every such hint; it is often the key that settles a marriage question.
Answer as per the official UPSC answer key.
A person climbs a hill in a straight path from point 'O' on the ground in the direction of north-east and reaches a point 'A' after travelling a distance of 5 km. Then, from the point 'A' he moves to point 'B' in the direction of north-west. Let the distance AB be 12 km. Now, how far is the person away from the starting point 'O' ?
Answer (b) & explanation
He is 13 km from the start (b). Step 1: north-east and north-west are at right angles to each other. So O, A and B form a right-angled triangle. Step 2: square the two short sides and add them: 5 × 5 + 12 × 12 = 25 + 144 = 169. Step 3: 13 × 13 = 169, so the distance OB is 13 km. Option (a), 7 km, is 12 − 5. Option (c), 17 km, is 12 + 5. Option (d), 11 km, does not fit.
Tip: learn the common right-triangle sets: 3-4-5, 5-12-13, 8-15-17 and 7-24-25. Seeing 5 and 12 should make you think of 13 at once.
Answer as per the official UPSC answer key.
30 g of sugar was mixed in 180 ml water in a vessel A, 40 g of sugar was mixed in 280 ml of water in vessel B and 20 g of sugar was mixed in 100 ml of water in vessel C. The solution in vessel B is :
Answer (d) & explanation
Vessel B is less sweet than vessel C (d). Step 1: sweetness = sugar ÷ water. A = 30/180 = 1/6. B = 40/280 = 1/7. C = 20/100 = 1/5. Step 2: compare the fractions. 1/5 is bigger than 1/6, which is bigger than 1/7. So C is sweetest and B is least sweet. Step 3: so B is less sweet than C, option (d). Option (a) says the opposite. Option (b) is wrong because B is less sweet than A too. Option (c) is wrong because B and C are not equal.
Tip: to compare mixtures, turn each into "per unit" form and simplify. With the same numerator 1, a smaller denominator means a stronger mixture.
Answer as per the official UPSC answer key.
Ram and Shyam work on a job together for four days and complete 60% of it. Ram takes leave then and Shyam works for eight more days to complete the job. How long would Ram take to complete the entire job alone?
Answer (c) & explanation
Ram alone would take 10 days (c). Step 1: together, 60% in 4 days means 15% per day together. Step 2: Shyam alone finishes the last 40% in 8 days, so Shyam does 5% per day. Step 3: Ram's rate = 15% − 5% = 10% per day. The whole job takes Ram 100 ÷ 10 = 10 days. Option (a), 6 days, and option (b), 8 days, are too fast. Option (d), 11 days, is too slow.
Tip: turn work into "percent per day" or "units per day". Rates add when people work together, so you can subtract to find one person's rate. Check: Ram and Shyam do 10% + 5% = 15% a day, which matches.
Answer as per the official UPSC answer key.
A ate grapes and pineapple; B ate grapes and oranges; C ate oranges, pineapple and apple; D ate grapes, apple and pineapple. After taking fruits, B and C fell sick. In the light of the above facts, it can be said that the cause of sickness was :
Answer (d) & explanation
The cause of sickness was oranges (d). Step 1: B and C fell sick. A and D stayed well. Look for a fruit that both sick people ate and neither healthy person ate. Step 2: B ate grapes and oranges. C ate oranges, pineapple and apple. The fruit common to B and C is oranges. Step 3: check the healthy pair. A ate grapes and pineapple, and D ate grapes, apple and pineapple. Neither ate oranges. Apple (a) and pineapple (b) were eaten by A or D, who stayed well. Grapes (c) were eaten by both A and D.
Tip: in "find the cause" puzzles, the cause appears in every bad case and in none of the good ones. Remove anything a healthy person also had.
Answer as per the official UPSC answer key.
A piece of tin is in the form of a rectangle having length 12 cm and width 8 cm. This is used to construct a closed cube. The side of the cube is :
Answer (c) & explanation
The side of the cube is 4 cm (c). Step 1: the tin sheet's area is 12 × 8 = 96 cm². Step 2: a closed cube has 6 equal square faces. So each face = 96 ÷ 6 = 16 cm². Step 3: 16 = 4 × 4, so each side is 4 cm. Option (a), 2 cm, gives only 24 cm² of surface. Option (b), 3 cm, gives 54 cm². Option (d), 6 cm, would need 216 cm², more than the sheet.
Tip: the surface area of a cube is 6 × side × side. When a sheet is "used to make" a solid, set the sheet's area equal to the solid's surface area, not its volume.
Answer as per the official UPSC answer key.
Read the passage
Historically, the biggest challenge to world agriculture has been to achieve a balance between demand for and supply of food. At the level of individual countries, the demand-supply balance can be a critical policy issue for a closed economy, especially if it is a populous economy and its domestic agriculture is not growing sufficiently enough to ensure food supplies, on an enduring basis; it is not so much and not always, of a constraint for an open, and growing economy, which has adequate exchange surpluses to buy food abroad. For the world as a whole, supply-demand balance is always an inescapable prerequisite for warding off hunger and starvation. However, global availability of adequate supply does not necessarily mean that food would automatically move from countries of surplus to countries of deficit if the latter lack in purchasing power. The uneven distribution of hunger, starvation, under- or malnourishment, etc., at the world-level, thus owes itself to the presence of empty-pocket hungry mouths, overwhelmingly confined to the underdeveloped economies. Inasmuch as ‘a two-square meal’ is of elemental significance to basic human existence, the issue of worldwide supply of food has been gaining significance, in recent times; both because the quantum and the composition of demand has been undergoing big changes, and because, in recent years, the capabilities of individual countries to generate uninterrupted chain of food supplies have come under strain. Food production, marketing and prices, especially price-affordability by the poor in the developing world, have become global issues that need global thinking and global solutions.
The issue of worldwide supply of food has gained importance mainly because of :
- 1. overgrowth of the population worldwide
- 2. sharp decline in the area of food production
- 3. limitation in the capabilities for sustained supply of food
Select the correct answer using the code given below :
Answer (b) & explanation
Only statement 3 is the reason (b). Step 1: the passage says world food supply matters because "the capabilities of individual countries to generate uninterrupted chain of food supplies have come under strain". That is statement 3, the limit on steady supply. Step 2: population overgrowth (1) is not stated as the reason. Step 3: a sharp fall in food-growing area (2) is also not stated. So options (a), (c) and (d) fail.
Tip: avoid choosing an option just because it is true in real life. Population growth does raise food demand, but the question asks what the passage gives as the reason. Stay inside the passage.
Answer as per the official UPSC answer key.
(Same information as the question above.)
Who is the lawyer ?
Answer (b) & explanation
Q is the lawyer (b). Step 1: the jobs are doctor, lawyer and artist. P and S are students, so the jobs belong to Q, R and T. Step 2: Q is neither doctor nor artist. The only job left for Q is lawyer. Step 3: check the rest. R is not the doctor, so R is the artist and T is the doctor. Option (a) P and option (d) S are students. Option (c) R is the artist.
Tip: a clue that rules out two of three choices fixes the third straight away. Look for such clues first. Here the clue about Q settles the lawyer before you need anything else.
Answer as per the official UPSC answer key.
An agricultural field is in the form of a rectangle having length X1 meters and breadth X2 meters (X1 and X2 are variable). If X1 + X2 = 40 meters, then the area of the agricultural field will not exceed which one of the following values?
Answer (a) & explanation
The area cannot exceed 400 sq m (a). Step 1: length + breadth = 40 m. Step 2: for a fixed sum, the product is largest when the two parts are equal. So the best is 20 × 20. Step 3: maximum area = 400 sq m. Try others: 30 × 10 = 300 and 35 × 5 = 175, both smaller. So options (b) 300, (c) 200 and (d) 80 are possible areas, but the question asks for the value it will not exceed.
Tip: among rectangles with the same perimeter, the square has the largest area. This idea comes up often in CSAT.
Answer as per the official UPSC answer key.
In aid of charity, every student in a class contributes as many rupees as the number of students in that class. With the additional contribution of Rs. 2 by one student only, the total collection is Rs. 443. Then how many students are there in the class?
Answer (b) & explanation
There are 21 students (b). Step 1: each student gives as many rupees as there are students. With n students, the total is n × n = n². Step 2: one student gives Rs 2 extra, so n² + 2 = 443, which gives n² = 441. Step 3: 21 × 21 = 441, so n = 21. Option (a), 12, gives only 144. Options (c) 43 and (d) 45 are traps built from the digits of 443 and 441.
Tip: when a total is "n times n", look for a perfect square near the number. Learning squares up to 30 by heart saves a lot of time in CSAT. Check: 21 × 21 + 2 = 443, which matches.
Answer as per the official UPSC answer key.
A military code writes SYSTEM as SYSMET and NEARER as AENRER. Using the same code, FRACTION can be written as :
Answer (d) & explanation
FRACTION is written as CARFNOIT (d). Step 1: look at SYSTEM → SYSMET. Split it into halves: SYS | TEM. Each half is written backwards: SYS stays SYS, and TEM becomes MET. Step 2: check with NEARER → AENRER. NEA becomes AEN, and RER stays RER. The rule holds. Step 3: FRACTION splits into FRAC | TION. Reversed: CARF | NOIT, giving CARFNOIT. Option (a), CARFTION, reverses only the first half. Option (b), FRACNOIT, reverses only the second half. Option (c), NOITCARF, reverses the whole word.
Tip: in coding questions, test a rule on both examples before using it. Palindrome halves like SYS can hide the pattern.
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. The rate of population growth is increasing in the country
- 2. The death rate is declining faster in the country compared to birth rate
- 3. The birth rate is declining faster in the country compared to death rate
- 4. Rural-urban migration is taking place regularly in the country
Which one of the following conclusions may be true in the light of the above facts ?
Answer (d) & explanation
Population growth rises because the death rate falls faster than the birth rate (d). Step 1: growth = birth rate − death rate. If the death rate falls faster than the birth rate, the gap between them widens. So growth rises. This matches statements 1 and 2. Step 2: option (a) blames migration. But people moving from villages to cities stay in the same country, so the national total does not change. Step 3: options (b) and (c) use the word only. The facts show both rates falling, so neither single cause explains it. Statement 3 contradicts statement 2, so it cannot be used.
Tip: population growth is simply births minus deaths, plus or minus migration across the border. Internal migration never changes the national count.
Answer as per the official UPSC answer key.