UPSC Prelims PYQs with explanations
Real questions from official papers, mapped to syllabus topics. Attempt each one; the answer and the reason appear instantly.
ABCD is a square. One point on each of AB and CD; and two distinct points on each of BC and DA are chosen. How many distinct triangles can be drawn using any three points as vertices out of these six points?
Answer (c) & explanation
20 triangles can be drawn (c). Step 1: any 3 of the 6 points make a triangle, unless all 3 lie on one straight line. Step 2: the most points on any one side is 2. So no three chosen points are in a line. Step 3: the number of ways to choose 3 from 6 = (6 × 5 × 4) ÷ (3 × 2 × 1) = 20. Options (a), (b) and (d) wrongly subtract or add cases.
Tip: number of triangles = C(n, 3) minus the groups of 3 points that are in a line. Here there are none to subtract.
Answer as per the official UPSC answer key.
Read the passage
Household finance in India is unique. We have a tendency to invest heavily in physical assets such as gold and property. Steps to encourage the financialization of savings are critical. A populace accustomed to traditional processes will not simply jump into financialization. Hurdles to change include onerous bureaucracy, a scepticism of organized financial institutions, a lack of basic information about which of the myriad services and providers is best for each family, and how (and even if) one can make the transition between them if necessary.
Regarding the financialization of household savings, which of the following statements best reflect the solutions that are implied by the passage ?
- 1. A flexible environment is needed to develop solutions.
- 2. Households need customised solutions.
- 3. Innovations in financial technology are required.
Select the correct answer using the code given below :
Answer (d) & explanation
All three solutions are implied (d). Step 1: the passage lists hurdles to financialising savings. "Onerous bureaucracy" implies the need for a flexible environment (1). Step 2: the lack of information on which service is "best for each family" implies customised solutions (2). Step 3: the lack of information and the difficulty of moving between providers imply the need for fintech innovation (3). So options (a), (b) and (c) fail.
Tip: when a passage lists problems, each problem implies its own solution. Match them one by one. Indians traditionally save in gold and property, which this passage calls physical assets.
Answer as per the official UPSC answer key.
Consider the following fauna :
- 1. Lion-tailed Macaque
- 2. Malabar Civet
- 3. Sambar Deer
How many of the above are generally nocturnal or most active after sunset?
Answer (a) & explanation
Only one of them is nocturnal (a). The Malabar civet, a critically endangered and possibly extinct animal of the Western Ghats, is active at night, like most civets. Item 1 is wrong: the lion-tailed macaque, also of the Western Ghats, is active by day, like most monkeys. Item 3 is treated as wrong: UPSC's key regards the sambar as feeding mainly around dawn and dusk rather than through the night, though it does turn nocturnal where hunted.
Notice the terms: nocturnal (night), diurnal (day) and crepuscular (dawn and dusk). Animals active at night often have big eyes, a sharp sense of smell or good hearing. The lion-tailed macaque is endangered, found only in rainforest canopies of Kerala, Karnataka and Tamil Nadu.
Answer as per the official UPSC answer key.
With reference to ancient Indian History, consider the following pairs :
| Literary work | Author
| 1. Devichandragupta | Bilhana
| 2. Hammira-Mahakavya | Nayachandra Suri
| 3. Milinda-panha | Nagarjuna
| 4. Nitivakyamrita | Somadeva Suri
How many of the above pairs are correctly matched?
Answer (b) & explanation
Two pairs are correctly matched (b). Pair 2 is right: Nayachandra Suri wrote the Hammira-Mahakavya on the Chauhan king Hammira of Ranthambhore. Pair 4 is right: Somadeva Suri wrote the Nitivakyamrita, a Jain work on statecraft. Pair 1 is wrong: the Devichandragupta is a play by Vishakhadatta, who also wrote the Mudrarakshasa; Bilhana wrote the Vikramankadevacharita. Pair 3 is wrong: the Milinda-panha records the dialogue of the monk Nagasena with the Indo-Greek king Menander; its author is unknown, and Nagarjuna is not linked to it.
Notice the theme of the Devichandragupta: it tells how Chandragupta II killed a Shaka king to save Queen Dhruvadevi, a story used to fill gaps in Gupta history.
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. In India, the Biodiversity Management Committees are key to the realization of the objectives of the Nagoya Protocol.
- 2. The Biodiversity Management Committees have important functions in determining access and benefit sharing, including the power to levy collection fees on the access of biological resources within its jurisdiction.
Which of the statements given above is/are correct?
Answer (c) & explanation
Both statements are correct (c). Statement 1 is right: under the Biological Diversity Act, 2002, every local body, such as a panchayat or municipality, sets up a Biodiversity Management Committee. BMCs are key to the Nagoya Protocol's aim of fair and equitable sharing of benefits from biological resources and traditional knowledge, because they bring it down to villages. Statement 2 is right: BMCs keep the People's Biodiversity Register, are consulted on access to local resources, and may levy collection fees on those who take resources from their area.
Notice the three-tier structure: the National Biodiversity Authority in Chennai, State Biodiversity Boards and BMCs. The Act was amended in 2023 to ease rules for AYUSH practitioners and research.
Answer as per the official UPSC answer key.
If ABC and DEF are both 3-digit numbers such that A, B, C, D, E and F are distinct non-zero digits such that ABC + DEF = 1111, then what is the value of A + B + C + D + E + F ?
Answer (d) & explanation
The sum of the six digits is 31 (d). Step 1: units place: C + F must end in 1. Two non-zero digits cannot add to 1, so C + F = 11, carrying 1. Step 2: tens place: B + E + 1 must end in 1, so B + E = 10, carrying 1. Step 3: hundreds place: A + D + 1 = 11, so A + D = 10. Total = 11 + 10 + 10 = 31. Options (a), (b) and (c) miss the carries.
Tip: in addition puzzles, work from the units place and track the carry at each step.
don't forget the carries. Without them you get 1 + 1 + 1 per column and land on a wrong option.
Answer as per the official UPSC answer key.
Read the passage
Scientists studied the vernal window — transition period from winter to the growing season. They found that warmer winters with less snow resulted in a longer lag time between spring events and a more protracted vernal window. This change in the spring timetable has ecological, social and economic consequences — for agriculture, fisheries and tourism. As the ice melts earlier, the birds don’t return, causing a delay, or lengthening in springtime ecological events.
With reference to the above passage, the following assumptions have been made :
- 1. Global warming is causing spring to come early and for longer durations.
- 2. Early spring and longer period of spring is not good for bird populations.
Which of the above assumptions is/are correct ?
Answer (a) & explanation
Only assumption 1 is correct (a). Step 1: the passage says warmer winters with less snow cause a "more protracted vernal window" and earlier ice melt. So global warming makes spring come early and last longer (1). Step 2: it says birds don't return on time, delaying spring events. Step 3: but it does not say bird populations suffer. Late return is not the same as harm to numbers. So assumption 2 fails, and options (b), (c) and (d) fail.
Tip: "vernal" means spring. A change in timing is not proof of a fall in numbers; don't stretch the passage.
Answer as per the official UPSC answer key.
Read the passage
“The last end of the state is not to dominate men, nor to restrain them by fear; rather it is so to free each man from fear that he may live and act with full security and without injury to himself or his neighbour. The end of the state, I repeat, is not to make rational beings into brute beasts and machines. It is to enable their bodies and their minds to function safely. It is to lead men to live by, and to exercise, a free reason; that they may not waste their strength in hatred, anger and guile, nor act unfairly toward one another.”
Based on the above passage, which one of the following terms best expresses the ultimate goal of the state ?
Answer (d) & explanation
The ultimate goal of the state is liberty (d). Step 1: the passage says the state's end is "not to dominate men" but to "free each man from fear". Step 2: it adds that the state should lead men to live by and use "a free reason". Freedom runs through every line. That is (d). Step 3: option (a), personal safety, and option (b), health of body and mind, are only parts of this freedom. Option (c), communal harmony, is a side effect at most.
Tip: this is Spinoza's view: "the end of the state is really liberty". Pick the term that sums up all the lines, not one detail.
Answer as per the official UPSC answer key.
Consider the following markets :
- 1. Government Bond Market
- 2. Call Money Market
- 3. Treasury Bill Market
- 4. Stock Market
How many of the above are included in capital markets?
Answer (b) & explanation
Two of them belong to the capital market (b). The capital market deals in long-term funds, over one year. It includes the stock market (item 4), where shares are traded, and the government bond market (item 1), where long-dated bonds are bought and sold. The money market deals in funds for up to one year. Item 2 is wrong: call money is borrowing between banks for one day, up to 14 days for notice money. Item 3 is wrong: Treasury Bills are short-term government papers of 91, 182 and 364 days.
Notice the regulators: SEBI watches the capital market, while the RBI looks after the money market and government securities. Commercial paper and certificates of deposit are other money market tools.
both bonds and T-Bills are government paper. What decides the market is maturity, not the issuer.
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. Ballistic missiles are jet-propelled at subsonic speeds throughout their flights, while cruise missiles are rocket-powered only in the initial phase of flight.
- 2. Agni-V is a medium-range supersonic cruise missile, while BrahMos is a solid-fuelled intercontinental ballistic missile.
Which of the statements given above is/are correct?
Answer (d) & explanation
Neither statement is correct (d). Statement 1 swaps the two types. A ballistic missile is rocket-powered only in its initial boost phase, then follows a high free-fall arc to its target. A cruise missile is jet-propelled throughout its flight, flying low like an aircraft. Statement 2 is also swapped: Agni-V is a solid-fuelled ballistic missile with a range above 5,000 km, while BrahMos, made with Russia, is a supersonic cruise missile flying at about Mach 2.8.
Notice that in 2024, under Mission Divyastra, India tested Agni-V with MIRV technology, letting one missile carry several warheads at different targets. BrahMos has been exported to the Philippines, India's first big missile export.
Answer as per the official UPSC answer key.
With reference to Home Guards, consider the following statements :
- 1. Home Guards are raised under the Home Guards Act and Rules of the Central Government.
- 2. The role of the Home Guards is to serve as an auxiliary force to the police in maintenance of internal security.
- 3. To prevent infiltration on the international border/coastal areas, the Border Wing Home Guards Battalions have been raised in some States.
How many of the above statements are correct?
Answer (b) & explanation
Two statements are correct (b). Statement 1 is wrong: Home Guards are raised under the Home Guards Acts and Rules of the States and Union Territories, not a central Act. Statement 2 is right: they are a voluntary force that works as an auxiliary to the police in keeping internal security, and helps in emergencies like floods, fires and disasters. Statement 3 is right: Border Wing Home Guards battalions have been raised in border States such as Punjab, Rajasthan, Gujarat and others to help the BSF stop infiltration.
Notice that the Home Guards were first raised in Bombay in 1946, during communal riots. Their policy is guided by the Directorate General of Fire Services, Civil Defence and Home Guards under the Union Home Ministry.
Answer as per the official UPSC answer key.
A, B, C working independently can do a piece of work in 8, 16 and 12 days respectively. A alone works on Monday, B alone works on Tuesday, C alone works on Wednesday; A alone, again works on Thursday and so on.
Consider the following statements :
- 1. The work will be finished on Thursday.
- 2. The work will be finished in 10 days.
Which of the above statements is/are correct ?
Answer (a) & explanation
Only statement 1 is correct (a). Step 1: take total work = 48 units (LCM of 8, 16, 12). A does 6, B does 3 and C does 4 units a day. One 3-day cycle = 13 units. Step 2: three cycles (9 days) = 39 units. Day 10 (A) brings it to 45. Day 11 (B) brings it to 48. The work ends on day 11. Step 3: day 1 is Monday, so day 8 is Monday again and day 11 is a Thursday. Statement 1 is true; statement 2 (10 days) is false.
Tip: in rotating-work problems, use LCM units and count full cycles first, then finish day by day.
the last day is a B day, and B needs a full day for the last 3 units. So it takes 11 days, not 10.
Answer as per the official UPSC answer key.
Read the passage
While awareness on use/misuse and abuse of antibiotics is common knowledge, as is the impact of dosing poultry with antibiotics, the environmental impact of antibiotics-manufacturing companies not treating their waste has scarcely been discussed at any length or seriousness thus far. Pollution from antibiotics factories is fuelling the rise of drug-resistant infections. The occurrence of drug-resistant bacteria surrounding the pharma manufacturing plants is well known.
Which one of the following statements best reflects the most logical and practical message conveyed by the passage ?
Answer (a) & explanation
The practical message is that proper effluent treatment protocols are needed (a). Step 1: the passage says antibiotic factories "not treating their waste" is fuelling drug-resistant infections. Step 2: the direct fix for untreated waste is proper treatment protocols. That is (a). Step 3: option (b), awareness, is already "common knowledge" as the passage says. Option (c) calls the problem unavoidable, which the passage does not say. Option (d), moving plants to rural areas, only shifts the harm elsewhere.
Tip: the most practical solution attacks the exact cause named. Antimicrobial resistance (AMR) is a key global health threat; India runs a National Action Plan on AMR.
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. India has more arable area than China.
- 2. The proportion of irrigated area is more in India as compared to China.
- 3. The average productivity per hectare in Indian agriculture is higher than that in China.
How many of the above statements are correct?
Answer (a) & explanation
Only one statement is correct (a). Statement 1 is right: India has about 156 million hectares of arable land, among the largest in the world and more than China's roughly 120 million. Statement 2 is wrong: by the data used for the question, China irrigated a larger share of its farmland than India, where much farming still depends on the monsoon. Statement 3 is wrong: China's yields per hectare of rice and wheat are much higher than India's, thanks to more fertiliser, seeds and mechanisation.
Notice the lesson: India's problem is not land but productivity. Small fragmented holdings, rain-fed farming and low investment hold it back, which is why schemes stress micro-irrigation and seeds.
India's big farm area tempts you to tick all three. Area is not productivity.
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. If the election of the President of India is declared void by the Supreme Court of India, all acts done by him/her in the performance of duties of his/her office of President before the date of decision become invalid.
- 2. Election for the post of the President of India can be postponed on the ground that some Legislative Assemblies have been dissolved and elections are yet to take place.
- 3. When a Bill is presented to the President of India, the Constitution prescribes time limits within which he/she has to declare his/her assent.
How many of the above statements are correct?
Answer (d) & explanation
None of the statements is correct (d). Statement 1 is wrong: Article 71(2) says acts done by the President before the election is declared void stay valid. Statement 2 is wrong: the election cannot be put off because some Assemblies stand dissolved, and under Article 71(4) the poll cannot be questioned on that ground. Statement 3 is wrong: Article 111 sets no time limit for assent. The President may give assent, withhold it, or return a non-money Bill once.
Notice the recent debate. In 2025, a Supreme Court bench set timelines for Governors in a Tamil Nadu case, but on a Presidential Reference later that year, a Constitution Bench held that courts cannot impose such fixed timelines. This is why people speak of the President's pocket veto.
"None" feels risky, so students force one statement to be true. Write T or F against each line first, then trust the count.
Answer as per the official UPSC answer key.
‘Aerial metagenomics’ best refers to which one of the following situations?
Answer (a) & explanation
Aerial metagenomics means collecting DNA from the air at one go (a). Animals and plants constantly shed tiny bits of DNA into the air, through skin, hair, pollen and spores. Aerial metagenomics filters air at one spot and reads all the DNA at once to list the species present, without seeing or catching them. It is part of environmental DNA (eDNA) methods. Option (b) is too narrow: it is not limited to birds. Option (c) is wrong: it does not take blood from animals. Option (d) describes drone sampling of land and water.
Notice that in 2022, scientists picked up DNA of animals in a zoo just by sampling the air. eDNA from water is already used to track fish and rare species.
"aerial" suggests birds or drones, but it refers to the air sample.
Answer as per the official UPSC answer key.
“Souls are not only the property of animal and plant life, but also of rocks, running water and many other natural objects not looked on as living by other religious sects.”
The above statement reflects one of the core beliefs of which one of the following religious sects of ancient India?
Answer (b) & explanation
This is a core belief of Jainism (b). Jainism holds that the world is full of jivas, or souls. Not only plants and animals but also earth, water, fire and air bodies have souls. Even these beings with just one sense, touch, are alive and can suffer. That is why Jain ahimsa is so strict: monks sweep their path, cover their mouths and strain water. Option (a) is wrong: Buddhism does not accept a permanent soul (anatta). Options (c) and (d), Shaivism and Vaishnavism, centre on devotion to a personal God, not souls in rocks and water.
Notice the Jain idea of anekantavada, many-sidedness of truth, and the three jewels: right faith, right knowledge and right conduct.
Answer as per the official UPSC answer key.
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.
Based on the above passage, the following assumptions have been made :
- 1. Collection, processing and segregation of municipal waste should be with government agencies.
- 2. Resource recovery and recycling require technological inputs that can be best handled by private sector enterprises.
Which of the assumptions given above is/are correct ?
Answer (d) & explanation
Neither assumption is correct (d). Step 1: the passage describes the problems: little segregation, recycling mostly by the informal sector, and three-fourths of the budget spent on collection and transport. Step 2: it never says who should run collection and segregation, so assumption 1 (government agencies) has no basis. Step 3: it never compares public and private firms on recycling technology, so assumption 2 fails too. Options (a), (b) and (c) fail.
Tip: an assumption must be needed for the author's argument. If the passage never discusses who should do a job, any "who" assumption is out.
Answer as per the official UPSC answer key.
Read the passage
Pharmaceutical patents grant protection to the patentee for the duration of the patent term. The patentees enjoy the liberty to determine the prices of medicines, which is time-limited to the period of monopoly, but could be unaffordable to the public. Such patent protection offered to the patentees is believed to benefit the public over the longer term through innovations and research and development (R&D), although it comes at a cost, in the nature of higher prices for the patented medicine. The patent regime and price protection — through a legally validated high price for the medicine during the currency of the patent — provide the patentee with a legitimate mechanism to get returns on the costs incurred in innovation and research.
Based on the above passage, the following assumptions have been made :
- 1. Patent protection given to patentees puts a huge burden on public’s purchasing power in accessing patented medicines.
- 2. Dependence on other countries for pharmaceutical products is a huge burden for developing and poor countries.
- 3. Providing medicines to the public at affordable prices is a key goal during the public health policy design in many countries.
- 4. Governments need to find an appropriate balance between the rights of patentees and the requirements of the patients.
Which of the above assumptions are valid ?
Answer (b) & explanation
Assumptions 1 and 4 are valid (b). Step 1: the passage says patent prices "could be unaffordable to the public". So patents can burden people's buying power (1). Step 2: it also says patents reward R&D and benefit the public in the long run. So governments must balance patent rights and patients' needs (4). Step 3: assumption 2, dependence on imports, and assumption 3, other countries' policy goals, are outside the passage. So options (a), (c) and (d) fail.
Tip: India's Patents Act Section 3(d) blocks "evergreening" of patents, an example of balancing innovation with access to medicines.
Answer as per the official UPSC answer key.
Which of the following organisms perform waggle dance for others of their kin to indicate the direction and the distance to a source of their food?
Answer (c) & explanation
Honeybees perform the waggle dance (c). A forager honeybee that finds food returns to the hive and does a figure-of-eight waggle dance on the comb. The angle of the waggle run, measured from straight up, shows the direction of the food relative to the Sun. The length of the run shows the distance. Other bees follow the dance and fly to the spot. Butterflies (a), dragonflies (b) and wasps (d) do not communicate this way.
Notice that Karl von Frisch decoded the dance and won the Nobel Prize in 1973. Bees matter far beyond honey: they pollinate many crops. India's National Beekeeping and Honey Mission pushes the Sweet Revolution.
Answer as per the official UPSC answer key.