UPSC Prelims PYQs with explanations
Real questions from official papers, mapped to syllabus topics. Attempt each one; the answer and the reason appear instantly.
What is ‘Greased Lightning-10 (GL-10)’, recently in the news?
Answer (a) & explanation
GL-10 Greased Lightning was an electric plane tested by NASA (a). This prototype drone had ten propellers driven by battery-electric motors, and its wings and tail tilted, so it could take off vertically like a helicopter and then fly like a plane. It was not a Japanese solar aircraft (b), a Chinese space observatory (c) or an ISRO reusable rocket (d).
NASA tested it in 2015 as part of work on quieter, efficient electric flight. Notice how its idea of distributed electric propulsion now drives the new field of eVTOL air taxis, which several companies, including Indian start-ups, are developing.
Answer as per the official UPSC answer key.
In the context of the history of India, consider the following pairs :
| Term | Description
| 1. Eripatti | Land, revenue from which was set apart for the maintenance of the village tank
| 2. Taniyurs | Villages donated to a single Brahmin or a group of Brahmins
| 3. Ghatikas | Colleges generally attached to the temples
Which of the pairs given above is/are correctly matched?
Answer (d) & explanation
Pairs 1 and 3 are correctly matched (d). In Chola and other south Indian inscriptions, eripatti ("tank land") was land whose income was set aside to maintain the village tank (1). Irrigation tanks were cared for by an eri-variyam (tank committee) of the village assembly. Ghatikas were centres of learning, usually attached to temples (3). The Kanchi ghatika is famous; the Kadamba founder Mayurasharma went there to study. Pair 2 is wrong because taniyurs were large villages made into separate revenue units. A village gifted to Brahmins was a brahmadeya, and one gifted to temples was a devadana.
Notice the Chola village assemblies: the ur (general villages) and the sabha (Brahmin villages). The Uttaramerur inscriptions describe how the sabha's members were chosen by lot.
Many taniyurs were brahmadeyas, so pair 2 looks close. The key wants brahmadeya for a gift to Brahmins.
Answer as per the official UPSC answer key.
Consider the following statement :
"We shall go either for a picnic or for trekking".
Which of the following, if true, would falsify this claim ?
Answer (d) & explanation
Only "we go for neither" falsifies the claim (d). Step 1: "We shall go either for a picnic or for trekking" means at least one of the two will happen. Step 2: such a claim is broken only when neither happens. So option (d) falsifies it. Step 3: test the others. Option (a), picnic but no trekking, fits the claim. Option (c), trekking but no picnic, also fits. Option (b), about health authorities, has nothing to do with whether the claim is true.
Tip: "either A or B" is false only when both are missing. "If A then B" is false only when A happens and B does not. Learn these two rules; they settle many logic questions.
Answer as per the official UPSC answer key.
Read the passage
Climate adaptation may be rendered ineffective if policies are not designed in the context of other development concerns. For instance, a comprehensive strategy that seeks to improve food security in the context of climate change may include a set of coordinated measures related to agricultural extension, crop diversification, integrated water and pest management and agricultural information services. Some of these measures may have to do with climate changes and others with economic development.
What is the most logical and rational inference that can be made from the above passage ?
Answer (d) & explanation
Climate adaptation should be examined together with other development options (d). Step 1: the passage says adaptation fails "if policies are not designed in the context of other development concerns". That is option (d). Step 2: option (c) says every development activity is linked to adaptation. The word "every" goes too far. Step 3: option (b) compares how complex food security and adaptation are, which the passage never does. Option (a), that adaptation is hard in developing countries, is not the main point.
Tip: the safest inference restates the author's main condition. Reject options with extreme words like "every" or comparisons the author never makes.
Answer as per the official UPSC answer key.
In a class of 60 students, where the number of girls is twice that of boys, Kamal, a boy, ranked seventeenth from the top. If there are 9 girls ahead of Kamal, the number of boys in rank after him is :
Answer (b) & explanation
12 boys rank after Kamal (b). Step 1: girls are twice the boys, and there are 60 students. So boys = 60 ÷ 3 = 20, girls = 40. Step 2: Kamal is 17th, so 16 students are ahead of him. Nine of them are girls, so 16 − 9 = 7 are boys. Step 3: boys after Kamal = 20 − 7 − 1 (Kamal himself) = 12. Option (a), 13, forgets to remove Kamal. Option (c), 7, is the boys ahead of him. Option (d), 3, does not fit.
Tip: in rank questions, always remember to count or remove the person himself. That is the most common mistake.
Answer as per the official UPSC answer key.
With reference to 'Stand Up India Scheme', which of the following statements is/are correct?
- 1. Its purpose is to promote entrepreneurship among SC/ST and women entrepreneurs.
- 2. It provides for refinance through SIDBI.
Select the correct answer using the code given below.
Answer (c) & explanation
Both statements are correct (c). Stand-Up India (April 2016) promotes entrepreneurship among SC/ST and women (1). Every bank branch should give at least one SC/ST and one woman borrower a loan of ₹10 lakh to ₹1 crore for a greenfield enterprise. SIDBI runs the scheme and provides refinance to banks (2), along with credit guarantee support through NCGTC.
The scheme has since been extended to 2025, and loans can also go to farm-allied activities. Notice how it sits beside Start-up India and MUDRA: MUDRA serves the smallest micro units, while Stand-Up India targets slightly bigger first-time ventures from groups that find credit hardest to get.
Answer as per the official UPSC answer key.
Which of the following statements is/are correct?
Viruses can infect
- 1. bacteria
- 2. fungi
- 3. plants
Select the correct answer using the code given below.
Answer (d) & explanation
All three are correct (d). Viruses can infect every kind of cellular life. Bacteriophages infect bacteria (1). The T4 phage is the classic example, and phages are now being tested as phage therapy against antibiotic-resistant germs. Mycoviruses infect fungi (2), and some are being explored as biocontrol agents. Plant viruses infect plants (3). Tobacco mosaic virus, the first virus ever discovered (Ivanovsky, 1892), is one example, along with banana bunchy top and cotton leaf curl.
Viruses also infect archaea, and even giant viruses can be attacked by virophages. Notice why viruses sit outside the five-kingdom classification: they have no cell machinery of their own. They are inert outside a host and come alive only inside a living cell.
Answer as per the official UPSC answer key.
Consider the following statements :
The Mangalyaan launched by ISRO
- 1. is also called the Mars Orbiter Mission
- 2. made India the second country to have a spacecraft orbit the Mars after USA
- 3. made India the only country to be successful in making its spacecraft orbit the Mars in its very first attempt
Which of the statements given above is/are correct?
Answer (c) & explanation
Statements 1 and 3 are correct (c). Mangalyaan, officially the Mars Orbiter Mission (MOM) (1), was launched by PSLV-C25 in November 2013. It entered Mars orbit on 24 September 2014, making India the first country to succeed on its first attempt (3). Statement 2 is wrong because the USSR, the USA and the European Space Agency had reached Mars orbit earlier. India was the fourth space agency to do it and the first in Asia. It cost about ₹450 crore, less than many Hollywood films.
It was meant to last six months but worked for about eight years, until 2022. Notice the next step, Mangalyaan-2, a planned orbiter, and remember that China's Tianwen-1 (2021) both orbited Mars and landed a rover.
Answer as per the official UPSC answer key.
Read the passage
Biomass as fuel for power, heat, and transport has the highest mitigation potential of all renewable sources. It comes from agriculture and forest residues as well as from energy crops. The biggest challenge in using biomass residues is a long-term reliable supply delivered to the power plant at reasonable costs; the key problems are logistical constraints and the costs of fuel collection. Energy crops, if not managed properly, compete with food production and may have undesirable impacts on food prices. Biomass production is also sensitive to the physical impacts of a changing climate.
Projections of the future role of biomass are probably overestimated, given the limits to the sustainable biomass supply, unless breakthrough technologies substantially increase productivity. Climate-energy models project that biomass use could increase nearly four-fold to around 150 — 200 exajoules, almost a quarter of world primary energy in 2050. However the maximum sustainable technical potential of biomass resources (both residues and energy crops) without disruption of food and forest resources ranges from 80 — 170 exajoules a year by 2050, and only part of this is realistically and economically feasible. In addition, some climate models rely on biomass-based carbon capture and storage, an unproven technology, to achieve negative emissions and to buy some time during the first half of the century.
Some liquid biofuels such as corn-based ethanol, mainly for transport, may aggravate rather than ameliorate carbon emissions on a life-cycle basis. Second generation biofuels, based on ligno-cellulosic feedstocks — such as straw, bagasse, grass and wood — hold the promise of sustainable production that is high-yielding and emit low levels of greenhouse gases, but these are still in the R & D stage.
What is/are the present constraint/constraints in using biomass as fuel for power generation ?
- 1. Lack of sustainable supply of biomass
- 2. Biomass production competes with food production
- 3. Bio-energy may not always be low carbon on a life-cycle basis
Select the correct answer using the code given below :
Answer (d) & explanation
All three constraints are right (d). Step 1: the passage mentions limits to "sustainable biomass supply". So statement 1, lack of a steady supply, is a constraint. Step 2: it says energy crops "compete with food production". So statement 2 is a constraint too. Step 3: it adds that biofuels "may aggravate" emissions "on a life-cycle basis". So bio-energy is not always low carbon, and statement 3 is right as well. Options (a), (b) and (c) each leave out at least one of the stated limits.
Tip: when every statement matches a line in the passage, pick "all of the above". Do not leave one out just because the full option seems too easy.
Answer as per the official UPSC answer key.
A person is standing on the first step from the bottom of a ladder. If he has to climb 4 more steps to reach exactly the middle step, how many steps does the ladder have?
Answer (b) & explanation
The ladder has 9 steps (b). Step 1: he is on step 1 and climbs 4 more steps, so the middle step is step 5. Step 2: a middle step has the same number of steps below and above it. There are 4 steps below step 5. So there must be 4 above. Step 3: total = 4 + 1 + 4 = 9 steps. Option (a), 8, has no single middle step. Option (c), 10, also has no single middle step. Option (d), 11, would put the middle at step 6.
Tip: a "middle" item exists only when the total is odd. For an odd total n, the middle item is number (n + 1) ÷ 2. Here (9 + 1) ÷ 2 = 5, which checks out.
Answer as per the official UPSC answer key.
With reference to ‘LiFi’, recently in the news, which of the following statements is/are correct?
- 1. It uses light as the medium for high-speed data transmission.
- 2. It is a wireless technology and is several times faster than ‘WiFi’.
Select the correct answer using the code given below.
Answer (c) & explanation
Both are correct (c). Li-Fi sends data through LED light that flickers too fast for the eye to see (1). It is wireless, and lab tests have reached speeds many times faster than Wi-Fi (2).
The idea was popularised by Harald Haas in 2011. Because light does not pass through walls, Li-Fi is more secure but limited to one room, and it needs line of sight. It can work where radio waves cause problems, such as aircraft cabins, hospitals and underwater. Notice how the same visible light that lets us see can also carry information.
Answer as per the official UPSC answer key.
India's ranking in the 'Ease of Doing Business Index' is sometimes seen in the news. Which of the following has declared that ranking?
Answer (c) & explanation
The World Bank published the Ease of Doing Business ranking through its annual Doing Business report (c). The OECD (a) works on economic policy for rich countries, the World Economic Forum (b) publishes the Global Competitiveness Report, and the WTO (d) deals with trade rules; none ran this index.
India climbed from 142nd in the 2015 report to 63rd in the 2020 report, helped by reforms such as the IBC and GST. After data irregularities came to light, the World Bank discontinued the report in 2021. Its replacement is B-READY (Business Ready). Notice how rankings can shape both policy and investor perception.
Answer as per the official UPSC answer key.
Which of the following is not a member of ‘Gulf Cooperation Council’?
Answer (a) & explanation
Iran is not a GCC member (a). The Gulf Cooperation Council was formed in 1981 with its headquarters in Riyadh. It has six Arab monarchies: Saudi Arabia (b), the UAE, Kuwait (d), Qatar, Bahrain and Oman (c). It was formed partly as a response to the 1979 Iranian Revolution and the Iran–Iraq war, so Iran's absence is the point. Iraq and Yemen are not members either.
For India, the GCC is a top trading bloc, a key oil and gas source, and home to about 9 million Indians, who send large remittances. India–GCC FTA talks restarted in 2022, and India signed a CEPA with the UAE in 2022. Notice the corridors too: IMEC, announced in 2023, runs through the UAE and Saudi Arabia.
Answer as per the official UPSC answer key.
The ‘Swadeshi’ and ‘Boycott’ were adopted as methods of struggle for the first time during the
Answer (a) & explanation
Swadeshi and Boycott were first adopted during the agitation against the Partition of Bengal (a). The boycott resolution passed at Calcutta Town Hall on 7 August 1905 launched the Swadeshi movement. The Home Rule Movement (b) came in 1916, Non-Cooperation (c) in 1920, and the Simon Commission (d) protests in 1928, all later.
The movement saw bonfires of foreign cloth, national schools, swadeshi industries and Tagore's Raksha Bandhan. The partition was annulled in 1911. Notice how methods first tried in 1905 became the backbone of Gandhian mass movements, which is why the Bengal agitation is called a dress rehearsal for later struggles.
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. Either A and B are of the same age or A is older than B
- 2. Either C and D are of the same age or D is older than C
- 3. B is older than C
Which of the following conclusions can be drawn from the above statements ?
Answer (d) & explanation
A is older than C (d). Step 1: write each statement as a sign. Statement 1: A is the same age as or older than B, so A ≥ B. Statement 2: D ≥ C. Statement 3: B > C. Step 2: join them: A ≥ B and B > C, so A > C for certain. Step 3: test the others. Option (a), A older than B, is only possible, since A and B may be equal. Option (c), D older than C, is also only possible, since they may be equal. Option (b), B and D the same age, is never linked by any statement.
Tip: turn age words into ≥ and > signs. A chain with a strict ">" anywhere gives a strict ">" at the end.
Answer as per the official UPSC answer key.
Read the passage
As we look to 2050, when we will need to feed two billion more people, the question of which diet is best has taken on new urgency. The foods we choose to eat in the coming decades will have dramatic ramifications for the planet. Simply put, a diet that revolves around meat and dairy, a way of eating that is on the rise throughout the developing world, will take a greater toll on the world’s resources than one that revolves around unrefined grains, nuts, fruits and vegetables.
What is the critical message conveyed by the above passage ?
Answer (a) & explanation
The critical message is that more animal-based food puts a bigger burden on natural resources (a). Step 1: the passage says a diet rich in meat and dairy "will take a greater toll on the world's resources". That is option (a). Step 2: option (b) says plant diets are best for health in developing countries. But the passage judges diets by their effect on the planet, not on health. Step 3: option (c), about people changing habits regardless of health, is not the point. Option (d), that we do not know the best diet, misses the main concern.
Tip: animal food needs much more land, water and feed per calorie than plant food. This is a common theme in climate passages.
Answer as per the official UPSC answer key.
‘Rashtriya Garima Abhiyaan’ is a national campaign to
Answer (c) & explanation
Rashtriya Garima Abhiyan (2001) is a national campaign to eradicate manual scavenging and rehabilitate those freed from it (c). It is led by civil-society groups, with Jan Sahas at its core. It is not about the homeless (a), sex workers (b) or bonded labour (d), which have their own laws and schemes.
The Prohibition of Employment as Manual Scavengers and their Rehabilitation Act, 2013 bans the practice. The NAMASTE scheme (2023) focuses on the safety of sanitation workers. Notice how this links to dignity under Article 21 and the abolition of untouchability under Article 17.
Answer as per the official UPSC answer key.
With reference to 'Initiative for Nutritional Security through Intensive Millets Promotion', which of the following statements is/are correct?
- 1. This initiative aims to demonstrate the improved production and post-harvest technologies, and to demonstrate value addition techniques, in an integrated manner, with cluster approach.
- 2. Poor, small, marginal and tribal farmers have larger stake in this scheme.
- 3. An important objective of the scheme is to encourage farmers of commercial crops to shift to millet cultivation by offering them free kits of critical inputs of nutrients and microirrigation equipment.
Select the correct answer using the code given below.
Answer (c) & explanation
Statements 1 and 2 are correct (c). INSIMP (2011–12, under the RKVY) showed improved production and post-harvest technologies for millets in an integrated manner, using a cluster approach (1). Millets are grown mainly by poor, small, marginal and tribal farmers on dry land, so they have the largest stake (2). Statement 3 is wrong: shifting commercial-crop farmers to millets with free kits was never an aim.
INSIMP aimed to boost millet output and value addition. Notice how millets returned to the spotlight as "Shree Anna" during the International Year of Millets 2023, proposed by India, for their nutrition and climate resilience.
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. The International Solar Alliance was launched at the United Nations Climate Change Conference in 2015.
- 2. The Alliance includes all the member countries of the United Nations.
Which of the statements given above is/are correct?
Answer (a) & explanation
Only statement 1 is correct (a). India and France launched the International Solar Alliance on 30 November 2015 at COP21 in Paris (1). Its headquarters is in Gurugram, at the National Institute of Solar Energy campus. It became a treaty-based body in 2017. Statement 2 is wrong because membership is not automatic. It was first meant for about 121 solar-rich countries lying between the Tropics, and in 2020 it was opened to all UN members, but each country must sign and ratify the framework agreement. About 100+ have done so, not all UN members.
Its slogan is "One Sun, One World, One Grid" (OSOWOG). Notice related Indian-led groups too: CDRI for disaster-resilient infrastructure and the Global Biofuels Alliance (2023).
Answer as per the official UPSC answer key.
There were 50 faculty members comprising 30 males and the rest females. No male faculty member knew music, but many of the female faculty members did. The Head of the institution invited six faculty members to a tea party by draw of lots. At the party it was discovered that no member knew music. The conclusion is that :
Answer (d) & explanation
Nothing can be said about the gender mix of the party (d). Step 1: no male knew music. But only "many", not all, of the 20 women knew music. So some women may not know music. Step 2: the six chosen people knew no music. They could be all men, all women who do not know music, or a mix of both. Step 3: so option (a), only men, is not certain. Option (b), only non-musical women, is not certain. Option (c), both men and women, is also only possible. None of them must be true.
Tip: "many" and "some" never mean "all". When a group is chosen by lottery, any combination that fits the facts is possible, so be slow to draw a conclusion.
Answer as per the official UPSC answer key.