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.
A person bought a car and sold it for ₹ 3,00,000. If he incurred a loss of 20%, then how much did he spend to buy the car?
Answer (d) & explanation
He spent ₹ 3,75,000 on the car (d). Step 1: a 20% loss means he got back 80% of what he paid. Step 2: 80% = ₹ 3,00,000, so 1% = 3,00,000 ÷ 80 = ₹ 3,750. Step 3: 100% = ₹ 3,75,000. Check: 20% of 3,75,000 is 75,000, and 3,75,000 − 75,000 = 3,00,000. Option (a), ₹ 3,60,000, wrongly adds 20% of the selling price. Options (b) and (c) fail.
Tip: loss and profit % are always on the cost price. So cost = selling price ÷ (1 − loss%). Adding 20% to the selling price is the classic trap.
(a) adds 20% to 3,00,000. The 20% is of the buying price, not the selling price.
Answer as per the official UPSC answer key.
A car travels from a place X to place Y at an average speed of v km/hr, from Y to X at an average speed of 2v km/hr, again from X to Y at an average speed of 3v km/hr and again from Y to X at an average speed of 4v km/hr. Then the average speed of the car for the entire journey
Answer (b) & explanation
The average speed lies between v and 2v (b). Step 1: each trip covers the same distance d. Average speed = total distance ÷ total time, not the average of the speeds. Step 2: total time = d/v + d/2v + d/3v + d/4v = (d/v)(1 + ½ + ⅓ + ¼) = 25d/12v. Step 3: average speed = 4d ÷ 25d/12v = 48v/25 = 1·92v. That is between v and 2v. Option (c) is the trap from averaging the speeds (2·5v).
Tip: for equal distances, the average speed is the harmonic mean, always less than the simple average. Slow legs take more time, so they pull the average down.
the plain average of v, 2v, 3v, 4v is 2·5v. The car spends more time at low speed.
Answer as per the official UPSC answer key.
A family of two generations consisting of six members P, Q, R, S, T and U has three males and three females. There are two married couples and two unmarried siblings. U is P's daughter and Q is R's mother-in-law. T is an unmarried male and S is a male. Which one of the following is correct?
Answer (b) & explanation
R is S's wife (b). Step 1: Q is R's mother-in-law. So Q is in the older generation, and R married Q's child. Step 2: the two unmarried siblings must be T (unmarried male) and U (P's daughter). So R's spouse is the remaining child, S, a male. The couples are P–Q and S–R. Step 3: males: P, S, T. Females: Q, R, U. So R is S's wife. Option (a) fails because U is unmarried. Option (c) fails because S is married. So (d) fails too.
Tip: in family puzzles, first count generations and couples. Then place unmarried people; the married pairs follow.
Answer as per the official UPSC answer key.
What is the greatest length x such that 3½ m and 8¾ m are integral multiples of x?
Answer (d) & explanation
The greatest length is 1¾ m (d). Step 1: write both in quarter-metres: 3½ m = 14/4 and 8¾ m = 35/4. Step 2: HCF(14, 35) = 7. So x = 7/4 = 1¾ m. Step 3: check: 3½ = 2 × 1¾ and 8¾ = 5 × 1¾. Both are whole multiples. Option (c), 1¼, divides 8¾ (7 times) but not 3½. Options (a) and (b) fail too.
Tip: for the HCF of fractions, put them over a common denominator and take the HCF of the numerators. Or use HCF of numerators ÷ LCM of denominators.
Answer as per the official UPSC answer key.
Two Statements S1 and S2 are given below with regard to two numbers followed by a Question :
S1 : Their product is 21.
S2 : Their sum is 10.
Question : What are the two numbers?
Which one of the following is correct in respect of the above Statements and the Question?
Answer (c) & explanation
S1 and S2 together are sufficient, but neither alone (c). Step 1: S1 alone: two numbers with product 21 could be 1 and 21 or 3 and 7 (or even fractions). Not enough. Step 2: S2 alone: many pairs add to 10: 1 and 9, 2 and 8, and so on. Not enough. Step 3: together: among pairs with product 21, only 3 and 7 add to 10. Algebra agrees: x + y = 10 and xy = 21 give x² − 10x + 21 = 0, so x = 3 or 7. The numbers are fixed. Options (a), (b) and (d) fail.
Tip: a sum and a product together fix two numbers, since they make a quadratic with one pair of roots.
Answer as per the official UPSC answer key.
Read the passage
India has tremendous potential for solar energy. We all realize that we have to stop burning fossil fuels to meet our energy needs. But certain renewable resources are still going through their cost curves and learning curves to get the required amount of output. The Indian Government has strongly committed to its targets of reducing emissions by 33 per cent by 2030, and towards this it has initiated a strong push towards a gas-based economy and has also invested heavily in renewable energy. However, business houses are wary of investing too heavily in renewable energy at a time when the technology is not yet ready.
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 rushing renewables to market too soon may be costly (c). Step 1: the passage says renewables are "still going through their cost curves", meaning their prices are still falling. Business is wary while "the technology is not yet ready". So pushing them early is costly. That is (c). Step 2: option (a) predicts India will miss its 33% target. The passage does not predict this. Step 3: option (b), import gas instead of renewables, and option (d), more gas exploration, are not suggested.
Tip: a cost curve shows prices falling as technology matures. Solar power costs in India fell sharply over the last decade for this reason.
Answer as per the official UPSC answer key.
Let p, q, r and s be natural numbers such that p – 2016 = q + 2017 = r – 2018 = s + 2019. Which one of the following is the largest natural number?
Answer (c) & explanation
r is the largest (c). Step 1: call the common value k. Then p − 2016 = k gives p = k + 2016. q + 2017 = k gives q = k − 2017. Step 2: r − 2018 = k gives r = k + 2018. s + 2019 = k gives s = k − 2019. Step 3: compare: r has the biggest number added, so r is the largest. p is second. q and s are smaller. Options (a), (b) and (d) fail.
Tip: setting a chain of equal expressions to one letter, k, makes comparison easy. Watch the signs: "p minus 2016" means p is bigger than k, while "q plus 2017" means q is smaller than k.
Answer as per the official UPSC answer key.
Read the passage
Spanish ships in the late 16th century first brought the potato tuber from South America to Europe whereby in the early 19th century, it had become a reliable backup to cereal crops, particularly in the cold, rain-soaked soils of Ireland. The Irish were soon almost wholly dependent on the potato as their staple food. And they were planting primarily one prodigious variety, the ‘Lumper’ potato, whose genetic frailty would be cruelly exposed by the fungus ‘Phytophthora infestans’. In 1845, spores of the deadly fungus began spreading across the country, destroying nearly all the Lumpers in its path. The resulting famine killed or displaced millions.
Which one of the following statements best reflects the critical message of the passage?
Answer (d) & explanation
The critical message is that relying on one uniform food source is unwise (d). Step 1: the passage says the Irish depended almost wholly on one potato variety, and one fungus wiped it out, causing famine. So depending on a single, uniform food is risky. That is (d). Step 2: option (a), suitable soil and climate, misses the point; the potato grew well in Ireland. Step 3: option (c), some fungal infections cannot be stopped, is too general. Option (b), tubers cannot replace cereals, is not the message.
Tip: this is the Irish Potato Famine of the 1840s. It is the classic warning against monoculture and a reason to keep crop diversity.
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. The minimum number of points of intersection of a square and a circle is 2.
- 2. The maximum number of points of intersection of a square and a circle is 8.
Which of the above statements is/are correct?
Answer (b) & explanation
Only statement 2 is correct (b). Step 1: statement 1 says the minimum number of meeting points is 2. But a circle can lie completely away from the square, or fully inside without touching it. Then there are 0 points. So 1 is false. Step 2: statement 2: a circle can cut each of the 4 sides twice, when it is a bit larger than the inscribed circle. That gives 8 points. So 2 is true. Step 3: so options (a), (c) and (d) fail.
Tip: a straight line can meet a circle at most twice. Multiply by the number of sides to get the maximum for any polygon: a triangle gives 6, a square 8.
Answer as per the official UPSC answer key.
If in a particular year 12th January is a Sunday, then which one of the following is correct?
Answer (c) & explanation
12th July is a Sunday if the year is a leap year (c). Step 1: days from 12 January to 12 July = 31 (Jan) + 28 (Feb) + 31 (Mar) + 30 (Apr) + 31 (May) + 30 (Jun) = 181 days. In a leap year, February has 29, so it is 182. Step 2: 182 = 7 × 26, an exact number of weeks. So in a leap year, 12 July falls on the same day, Sunday. Step 3: option (d) says the opposite, so it fails. Options (a) and (b) about 15 July do not work: 15 July would be Wednesday (leap) or Tuesday (non-leap).
Tip: count days between dates and divide by 7. The remainder tells how many days the weekday moves forward.
Answer as per the official UPSC answer key.
Consider the following data :
| Year | Birthrate | Death rate |
|---|---|---|
| 1911–1921 | 48·1 | 35·5 |
| 1921–1931 | 46·4 | 36·3 |
| 1931–1941 | 45·2 | 31·2 |
| 1941–1951 | 39·9 | 27·4 |
| 1951–1961 | 41·7 | 22·8 |
| 1961–1971 | 41·1 | 18·9 |
| 1971–1981 | 37·1 | 14·8 |
For which period was the natural growth rate maximum?
Answer (d) & explanation
Natural growth rate was highest in 1971–1981 (d). Step 1: natural growth = birth rate − death rate. Step 2: from the table: 1911–21: 12·6; 1941–51: 12·5; 1961–71: 22·2; 1971–81: 22·3. Step 3: the biggest is 22·3, in 1971–1981. Option (c), 1961–71, is very close but slightly lower. Options (a) and (b) are much lower.
Tip: when two values are close, calculate carefully; UPSC often places a near-miss option. Historically, India's growth peaked around 1961–81 as death rates fell faster than birth rates.
1961–71 (22·2) is very close; subtract carefully.
Answer as per the official UPSC answer key.
A man walks down the backside of his house straight 25 metres, then turns to the right and walks 50 metres again; then he turns towards left and again walks 25 metres. If his house faces to the East, what is his direction from the starting point?
Answer (d) & explanation
He is North-West of his starting point (d). Step 1: the house faces East, so its back side faces West. He walks 25 m West. Step 2: facing West, a right turn points him North. He walks 50 m North. Facing North, a left turn points him West. He walks 25 m West. Step 3: net movement: 25 + 25 = 50 m West and 50 m North. Equal amounts of West and North give North-West. Options (a), (b) and (c) fail.
Tip: draw a quick sketch with N at the top. Remember: facing West, right is North and left is South. Equal moves in two directions give the in-between direction.
Answer as per the official UPSC answer key.
Read the passage
India has tremendous potential for solar energy. We all realize that we have to stop burning fossil fuels to meet our energy needs. But certain renewable resources are still going through their cost curves and learning curves to get the required amount of output. The Indian Government has strongly committed to its targets of reducing emissions by 33 per cent by 2030, and towards this it has initiated a strong push towards a gas-based economy and has also invested heavily in renewable energy. However, business houses are wary of investing too heavily in renewable energy at a time when the technology is not yet ready.
With reference to the above passage, the following assumptions have been made :
- 1. Governments often provide inefficient and costly subsidies for technologies that may not be ready in the near future.
- 2. India’s commitment of reducing emissions by 33% by 2030 shall be on the basis of gas-based economy.
Which of the above assumptions is/are valid?
Answer (a) & explanation
Only assumption 1 is valid (a). Step 1: UPSC's key reads the passage's point about heavy state support for a technology that is "not yet ready" as costly and inefficient subsidy (1). Step 2: assumption 2 says the 33% emissions target will rest on a gas-based economy. But the passage says the target depends on gas and renewables, not gas alone. So 2 fails. Step 3: so options (b), (c) and (d) fail.
Tip: watch for an option that keeps one part of a pair and drops the other. "Gas and renewables" does not mean "gas-based". India later updated its Paris goal to 45% lower emissions intensity by 2030 (from 2005 levels).
Answer as per the official UPSC answer key.
How many five-digit prime numbers can be obtained by using all the digits 1, 2, 3, 4 and 5 without repetition of digits?
Answer (a) & explanation
No such prime exists, so the answer is zero (a). Step 1: any number made from all of 1, 2, 3, 4 and 5 has a digit sum of 1 + 2 + 3 + 4 + 5 = 15. Step 2: 15 is divisible by 3, so every such number is divisible by 3. Step 3: a number divisible by 3 (and bigger than 3) is not prime. So there are zero such primes. Options (b), (c) and (d) fail.
Tip: before counting arrangements, check the digit sum. If it is divisible by 3, no arrangement can be prime. This trick saves you from listing 120 numbers.
Answer as per the official UPSC answer key.
Read the passage
India is at once among the fastest growing global economies and home to the largest number of malnourished children in the world. There are regions where malnutrition is not the exception but the norm. And across the country, malnutrition is the cause of death for roughly half the 1·3 million children who die before their fifth birthday each year. Even those children who survive suffer permanently from the damage that has already been done to their bodies and minds from not getting enough of the right foods and nutrients. Around 44 million children under 5 are stunted. That makes it harder for them to learn in school and subsequently earn a living as adults. Their lifetime earnings potential is almost a quarter less than that of their healthy peers.
With reference to the above passage, which of the following is/are the most rational and practical implication/implications?
- 1. India’s Public Distribution System should be monitored by the Union Government.
- 2. Girls should be encouraged to delay marriage and first pregnancy.
- 3. Mothers should be encouraged to breastfeed their children immediately after birth.
- 4. The supply of safe drinking water and proper sanitation facilities to all should be ensured.
- 5. Authorities should ensure the vaccination as prescribed.
Select the correct answer using the code given below.
Answer (b) & explanation
Implications 2, 3, 4 and 5 are rational and practical (b). Step 1: the passage says most damage from malnutrition happens before age five. So steps should target mothers and young children. Step 2: delaying marriage and first pregnancy (2), early breastfeeding (3), safe water and sanitation (4) and proper vaccination (5) all protect young children. Step 3: statement 1, Union monitoring of the PDS, is an administrative change the passage does not imply. So options (a), (c) and (d) fail.
Tip: India's legal minimum marriage age for women is 18. Breastfeeding within the first hour of birth is a key WHO advice point. Link each option to the passage's focus: early childhood.
Answer as per the official UPSC answer key.
A man takes half time in rowing a certain distance downstream than upstream. What is the ratio of the speed in still water to the speed of current?
Answer (d) & explanation
The ratio of speed in still water to current is 3 : 1 (d). Step 1: the same distance takes half the time downstream, so the downstream speed is double the upstream speed. Step 2: let the boat's speed be b and the current c. Downstream = b + c; upstream = b − c. So b + c = 2(b − c). Step 3: this gives b + c = 2b − 2c, so b = 3c. Ratio = 3 : 1. Option (b), 2 : 1, is the ratio of the speeds, not of boat to current. Options (a) and (c) fail.
Tip: downstream adds the current, upstream subtracts it. Half the time means double the speed for the same distance.
Answer as per the official UPSC answer key.
Read the passage
Private investment in general is volatile. Foreign private investment is more volatile because the available investment avenues are significantly greater (i.e., the entire world). Therefore, the responsibility of providing employment cannot be left to Foreign Direct Investment (FDI). The current FDI inflows are volatile over time and, across sectors and regions, which is a necessary consequence of their search for the highest returns. The adverse consequences are unstable employment and an accentuation of income and regional inequalities. A probable positive consequence of foreign investment is the inflow of new technology and its subsequent diffusion. However, the technology diffusion is not at all certain because the existing state of physical and human capital in India may prove inadequate for the diffusion.
With reference to the above passage, the following assumptions have been made :
- 1. Relying on foreign investment in the long run is not an economically sound policy.
- 2. Policies must be undertaken to reduce volatility in foreign private investment.
- 3. Policies must be undertaken to strengthen domestic private investment.
- 4. Public investment should be given priority over private investment.
- 5. Substantial public investment in education and health should be undertaken.
Which of the above assumptions is/are valid?
Answer (b) & explanation
Assumptions 1, 3 and 5 are valid (b). Step 1: the passage says jobs "cannot be left to FDI". So relying on foreign investment in the long run is unwise (1), and domestic private investment must be strengthened (3). Step 2: it says weak human capital blocks the spread of technology. So spending on education and health is needed (5). Step 3: assumption 2 fails because the passage calls FDI volatility a "necessary consequence", which policy cannot remove. Assumption 4, putting public over private investment, is not argued. So options (a), (c) and (d) fail.
Tip: if a passage calls something unavoidable, reject options that ask policy to prevent it.
Answer as per the official UPSC answer key.
The recurring decimal representation 1·272727... is equivalent to
Answer (b) & explanation
1·272727... equals 14/11 (b). Step 1: split it: 1 + 0·2727... Step 2: a two-digit repeating block over 99: 0·2727... = 27/99 = 3/11. Step 3: 1 + 3/11 = 14/11. Check: 14 ÷ 11 = 1·2727... Option (a), 13/11 = 1·1818... Option (c), 127/99 = 1·2828... Option (d), 137/99 = 1·3838... All fail.
Tip: for pure recurring decimals, put the repeating digits over as many 9s as there are digits: 0·ab ab... = ab/99. Then simplify. If one digit does not repeat, like 1·2333..., use 9s for repeating digits and 0s for the rest.
Answer as per the official UPSC answer key.
Two Statements are given followed by two Conclusions :
Statements : All numbers are divisible by 2. All numbers are divisible by 3.
Conclusion-I : All numbers are divisible by 6.
Conclusion-II : All numbers are divisible by 4.
Which of the above Conclusions logically follows/follow from the two given Statements?
Answer (a) & explanation
Only Conclusion I follows (a). Step 1: all numbers are divisible by 2 and by 3. Since 2 and 3 share no common factor, a number divisible by both is divisible by 2 × 3 = 6. So Conclusion I follows. Step 2: Conclusion II says all are divisible by 4. But being divisible by 2 does not mean divisible by 4. For example, 6 is divisible by 2 and 3, but not by 4. Step 3: so II does not follow. Options (b), (c) and (d) fail.
Tip: if a number is divisible by two co-prime numbers (no shared factor), it is divisible by their product. This does not work for 2 and 4, which share a factor.
Answer as per the official UPSC answer key.
Read the passage
Genome editing is different from genome modification. Genome editing typically involves finding the part of a plant genome that could be changed to render it less vulnerable to disease, or resistant to certain herbicides, or to increase yields. Researchers use ‘molecular scissors’ to dissect the genome and repair it, which is a process that occurs naturally when plants are under attack from diseases and can throw up new mutations that enable the plant to survive future attacks. This evolutionary process can effectively be speeded up now that it is possible to examine plant genomes in detail in laboratories, and create mechanisms through which the relevant genes can be altered very precisely.
With reference to the above passage, the following assumptions have been made :
- 1. Genome editing does not require the transfer of genes from one plant to another.
- 2. Through genome editing, the chosen genes can be altered precisely in a manner akin to the natural process that helps plants to adapt to the environmental factors.
Which of the above assumptions is/are valid?
Answer (c) & explanation
Both assumptions are valid (c). Step 1: the passage says genome editing changes a plant's own genes, unlike genetic modification, which moves genes from another organism. So editing does not need gene transfer (1). Step 2: it says editing speeds up a natural repair process and works "very precisely". So chosen genes can be changed precisely, much like nature's own way of adapting (2). Step 3: so options (a), (b) and (d) fail.
Tip: CRISPR is the best-known gene-editing tool. In May 2025, India released two genome-edited rice varieties, DRR Dhan 100 (Kamala) and Pusa DST Rice 1, the world's first such rice varieties.
Answer as per the official UPSC answer key.