UPSC Prelims PYQs with explanations
Real questions from official papers, mapped to syllabus topics. Attempt each one; the answer and the reason appear instantly.
Consider the following pairs :
| Port | Well known as
| 1. Kamarajar Port | First major port in India registered as a company
| 2. Mundra Port | Largest privately owned port in India
| 3. Visakhapatnam Port | Largest container port in India
How many of the above pairs are correctly matched?
Answer (b) & explanation
Two pairs are correctly matched (b). Pair 1 is right: Kamarajar Port at Ennore, near Chennai, was India's first major port set up as a public company, rather than a port trust. Pair 2 is right: Adani's Mundra Port in Gujarat is India's largest privately owned port. Pair 3 is wrong: Visakhapatnam is known for bulk cargo such as iron ore and coal. When asked, the largest container port was Jawaharlal Nehru Port (Nhava Sheva) near Mumbai, with Mundra close behind; Mundra has since moved ahead in container volume.
Notice the new Vadhavan port in Maharashtra, approved in 2024, planned as one of the world's top ten container ports. The Sagarmala programme aims at port-led development along India's coast.
Answer as per the official UPSC answer key.
In India, which one of the following Constitutional Amendments was widely believed to be enacted to overcome the judicial interpretations of the Fundamental Rights?
No official answer (question dropped) & notes
UPSC dropped this question, so no answer was counted. The ideas are still worth knowing. The 1st Amendment (1951) answered court rulings on land reform and free speech: it added the Ninth Schedule to shield land laws and new limits to Article 19(2). The 42nd Amendment (1976) also tried to put laws based on the Directive Principles beyond Fundamental Rights challenges. The 44th (1978) undid many Emergency changes, and the 86th (2002) made education a Fundamental Right. More than one option fits "widely believed", which is likely why it was dropped.
Notice the long tussle: courts struck down laws, Parliament amended, and Kesavananda Bharati (1973) finally set the basic structure limit on amendments.
UPSC did not evaluate this question, so no official answer exists. Use it for practice only.
UPSC dropped this question from evaluation; there is no official answer.
‘Wolbachia method’ is sometimes talked about with reference to which one of the following?
Answer (a) & explanation
The Wolbachia method is used to control viral diseases spread by mosquitoes (a). Wolbachia is a common bacterium found in many insects. When it is put into Aedes aegypti mosquitoes, it stops dengue, Zika and chikungunya viruses from multiplying inside them. Infected females pass it to their young, so it spreads through the wild mosquito population over time. Options (b), (c) and (d) are about crop residues, bioplastics and biochar, which have nothing to do with it.
Notice the results: the World Mosquito Program has cut dengue sharply in trial cities such as Yogyakarta in Indonesia. India's ICMR developed its own Wolbachia strains of Aedes mosquitoes in 2024. Another approach releases sterile male mosquitoes.
Answer as per the official UPSC answer key.
Consider the following statements about G-20 :
- 1. The G-20 group was originally established as a platform for the Finance Ministers and Central Bank Governors to discuss the international economic and financial issues.
- 2. Digital public infrastructure is one of India's G-20 priorities.
Which of the statements given above is/are correct?
Answer (c) & explanation
Both statements are correct (c). Statement 1 is right: the G-20 began in 1999, after the Asian financial crisis, as a meeting of finance ministers and central bank governors to discuss global economic issues. It was raised to leaders' level in 2008, after the global financial crisis. Statement 2 is right: during its 2023 presidency, India pushed digital public infrastructure, such as UPI and Aadhaar-style platforms, as a key priority, and the New Delhi Declaration endorsed it.
Notice India's other G-20 wins: the African Union became a permanent member, and the theme was "Vasudhaiva Kutumbakam", One Earth, One Family, One Future. India also launched the Global Biofuels Alliance. South Africa held the presidency in 2025, the first in Africa.
Answer as per the official UPSC answer key.
What is the sum of all digits which appear in all the integers from 10 to 100?
Answer (b) & explanation
The sum is 856 (b). Step 1: from 10 to 99, the tens place shows each digit 1 to 9 exactly 10 times. That gives 45 × 10 = 450. Step 2: the units place shows each digit 0 to 9 exactly 9 times (once per ten). That gives 45 × 9 = 405. Step 3: add the digits of 100, which is 1. Total = 450 + 405 + 1 = 856. Option (a), 855, forgets 100. Options (c) and (d) miscount.
Tip: count digit sums place by place. Each place cycles through the digits evenly.
don't drop the 100 at the end. 855 is the trap option.
Answer as per the official UPSC answer key.
Read the passage
The paradox of choice is illustrated by the story of Buridan’s ass. Jean Buridan, the 14th century philosopher, wrote about free will and the inability to choose due to numerous choices and uncertainties. In the story, a donkey stands between two equally appealing stacks of hay. Unable to decide which to eat, it starves to death. Changes in technology and innovations such as smart phones and tablets only exacerbate our glut of choices. Constant connectivity and overconsumption of real-time data and social media can leave little room for self-reflection and rest, making decisions more difficult. Life is about choices. Many people are overwhelmed with attractive life choices, yet find themselves unhappy and anxious.
Which one of the following statements best reflects the most logical message implied by the above passage ?
Answer (d) & explanation
The message is that too few choices may be bad, but too many can be just as hard (d). Step 1: the passage tells of Buridan's ass, which starved between two equally good stacks of hay because it could not choose. Step 2: it says technology adds to our "glut of choices", leaving people unhappy and anxious, yet "life is about choices". That is the paradox of choice, so (d). Step 3: option (b) calls the choices difficult; the passage calls them attractive. Option (a) blames technology for weakening society. Option (c), lacking courage, is not discussed.
Tip: "paradox" signals two sides. Pick the option that holds both: choices are needed, but too many overwhelm.
Answer as per the official UPSC answer key.
‘Invasive Species Specialist Group’ (that develops Global Invasive Species Database) belongs to which one of the following organizations?
Answer (a) & explanation
The ISSG belongs to the IUCN (a). The Invasive Species Specialist Group is one of the specialist groups of the IUCN Species Survival Commission, the same body behind the Red List. It runs the Global Invasive Species Database, which lists alien species that harm native life. Option (b) is wrong: UNEP runs global environment programmes but not this group. Option (c) is wrong: the World Commission on Environment and Development (Brundtland Commission) gave the 1987 report on sustainable development. Option (d) is wrong: WWF is a separate conservation NGO.
Notice India's major invasive species: Lantana, Parthenium (congress grass), water hyacinth and Prosopis juliflora. The Kunming-Montreal framework (2022) aims to cut the arrival of invasive species by half by 2030.
Answer as per the official UPSC answer key.
Consider the following dynasties :
- 1. Hoysala
- 2. Gahadavala
- 3. Kakatiya
- 4. Yadava
How many of the above dynasties established their kingdoms in early eighth century AD?
Answer (d) & explanation
None of them was founded in the early eighth century (d). All four are later dynasties. The Hoysalas of Karnataka rose in the 11th century, with capitals at Belur and Halebidu. The Gahadavalas took Kanauj around 1090. The Kakatiyas of Warangal and the Yadavas of Devagiri became independent in the 12th century, after the Western Chalukya power fell. So options (a), (b) and (c) are wrong.
Notice who did rise in the eighth century: the Rashtrakutas (Dantidurga, about 753), the Gurjara-Pratiharas and the Palas of Bengal. These three later fought the tripartite struggle for Kanauj. The Hoysalas are famous for star-shaped temples, now a UNESCO World Heritage site (2023).
"How many" with an option "None": dynasties of the 11th–13th centuries are put here to look as if they rose earlier.
Fell for this one? Most aspirants do. The PYQ Book puts every UPSC trap side by side, so the pattern finally clicks. Try the free sample
Answer as per the official UPSC answer key.
Which one of the following countries has been suffering from decades of civil strife and food shortages and was in news in the recent past for its very severe famine?
Answer (d) & explanation
Somalia has suffered civil strife and severe famine (d). Somalia has faced civil war since 1991 and the al-Shabaab insurgency since the mid-2000s. Five failed rainy seasons in a row (2020–23), the worst drought in decades, pushed it close to famine, after the deadly famines of 1992 and 2011, which killed about a quarter of a million people. Option (a) is wrong: Angola's civil war ended in 2002. Options (b) and (c) are wrong: Costa Rica and Ecuador in Latin America have not faced famine.
Notice the term IPC Phase 5, used by UN agencies to declare famine. In 2024, famine was confirmed in parts of Sudan, and in 2025 in Gaza. The Horn of Africa remains highly vulnerable to drought.
Answer as per the official UPSC answer key.
What is the unit digit in the expansion of (57242)9×7×5×3×1 ?
Answer (a) & explanation
The unit digit is 2 (a). Step 1: only the last digit of 57242 matters, which is 2. Powers of 2 end in the cycle 2, 4, 8, 6, of length 4. Step 2: the power is 9 × 7 × 5 × 3 × 1 = 945. 945 ÷ 4 leaves a remainder of 1. Step 3: remainder 1 gives the first term of the cycle: 2. Options (b), (c) and (d) are other cycle terms.
Tip: an odd power can never be a multiple of 4. A product of odd numbers is always odd, which quickly rules out the 4th term (6).
Answer as per the official UPSC answer key.
Choose the group which is different from the others :
Answer (d) & explanation
Group (d) is the odd one out (d). Step 1: check whether each number is prime. Groups (a) 17, 37, 47, 97; (b) 31, 41, 53, 67; and (c) 71, 73, 79, 83 contain only primes. Step 2: in group (d), 91 = 7 × 13, which is not prime. Step 3: so (d) is different. Options (a), (b) and (c) all fit the pattern.
Tip: 91 looks prime but is 7 × 13. Other common traps are 51 (3 × 17), 57 (3 × 19) and 87 (3 × 29).
91 looks prime but is 7 × 13. Learn this one by heart.
Answer as per the official UPSC answer key.
Read the passage
“Science by itself is not enough, there must be a force and discipline outside the sciences to coordinate them and point to a goal. It is not possible to run a course aright when the goal itself has not been rightly placed. What science needs is philosophy — the analysis of scientific method and the coordination of scientific purposes and results; without this, any science must be superficial. Government suffers, precisely like science, for lack of philosophy. Philosophy bears to science the same relationship which statesmanship bears to politics : movement guided by total knowledge and perspective, as against aimless and individual seeking. Just as the pursuit of knowledge becomes scholasticism when divorced from the actual needs of men and life, so the pursuit of politics becomes a destructive bedlam when divorced from science and philosophy.”
Which one of the following statements best reflects the most rational, logical and practical message conveyed by the passage ?
Answer (b) & explanation
The message is that government should not be run only by practical statesmen, but with people of learning and wisdom (b). Step 1: the passage says science needs philosophy to give it a goal. Step 2: it says government suffers "like science, for lack of philosophy". Politics without science and philosophy becomes "destructive bedlam". So practical statesmen need learned, wise people alongside. That is (b). Step 3: options (a) and (c) prescribe training schemes the passage never proposes. Option (d), all scientists as philosophers, is too absolute.
Tip: this passage is from Will Durant on Plato. Pick the option that applies the passage's comparison (science-philosophy, politics-statesmanship) to government.
Answer as per the official UPSC answer key.
Which one of the following activities of the Reserve Bank of India is considered to be part of 'sterilization'?
Answer (a) & explanation
Open Market Operations are used for sterilisation (a). When the RBI buys dollars to stop the rupee rising too fast, it pays in rupees, which adds money to the system and can push up inflation. To soak up that extra money, it sells government securities through open market operations. Cancelling the effect of forex operations on money supply this way is called sterilisation. Option (b) is wrong: overseeing payment systems is a separate RBI role. Option (c) is wrong: debt and cash management for governments is its banker role. Option (d) is wrong: regulating NBFCs is supervision.
Notice other sterilisation tools: the Market Stabilisation Scheme (2004), the Standing Deposit Facility (2022) and forex swaps, which avoid selling bonds.
Answer as per the official UPSC answer key.
Which one of the following countries has its own Satellite Navigation System?
Answer (d) & explanation
Japan has its own satellite navigation system (d). Japan's Quasi-Zenith Satellite System (QZSS), called Michibiki, is a regional system that boosts GPS accuracy over Japan and the Asia–Oceania region. Australia (a), Canada (b) and Israel (c) rely on others' systems. There are four global systems: GPS (USA), GLONASS (Russia), Galileo (European Union) and BeiDou (China). There are two regional systems: Japan's QZSS and India's NavIC.
Notice India's NavIC (IRNSS) covers India and about 1,500 km around it. Some of its satellites lost their atomic clocks, and ISRO is launching the new NVS series, starting with NVS-01 in 2023. Phones now carry chips that use NavIC.
Answer as per the official UPSC answer key.
Consider the following statements :
- 1. Recently, all the countries of the United Nations have adopted the first-ever compact for international migration, the ‘Global Compact for Safe, Orderly and Regular Migration (GCM)’.
- 2. The objectives and commitments stated in the GCM are binding on the UN member countries.
- 3. The GCM addresses internal migration or internally displaced people also in its objectives and commitments.
How many of the above statements are correct?
Answer (d) & explanation
None of the statements is correct (d). Statement 1 is wrong: the Global Compact for Safe, Orderly and Regular Migration was adopted at Marrakech in December 2018 and then endorsed by the General Assembly by vote. The USA and several other countries, such as Hungary, stayed out, so not all countries adopted it. Statement 2 is wrong: the GCM is non-binding; it sets 23 objectives but respects national sovereignty. Statement 3 is wrong: it covers international migration only, not internal migration or internally displaced people.
Notice its twin, the Global Compact on Refugees (2018). India supported the GCM. India is the world's largest source of migrants and receives the most remittances, over $125 billion a year.
Answer as per the official UPSC answer key.
How many distinct 8-digit numbers can be formed by rearranging the digits of the number 11223344 such that odd digits occupy odd positions and even digits occupy even positions?
Answer (c) & explanation
1. The odd digits are 1, 1, 3, 3. They go into the 4 odd places. Two places get 1 and two get 3. Choosing which two places get the 1s can be done in 6 ways (list them: 12, 13, 14, 23, 24, 34).
2. The even digits 2, 2, 4, 4 go into the 4 even places in the same way: 6 ways.
3. Each choice on one side goes with each choice on the other: 6 × 6 = 36.
Answer as per the official UPSC answer key.
Read the passage
Sourcing food from non-agricultural lands (uncultivated systems such as forests, wetlands, pastures, etc) in addition to agricultural lands enables a systemic approach to food consumption. It allows rural and tribal communities to sustain themselves for the whole year and steer clear of natural disasters and season-induced shortfalls of agricultural food. Since the productivity of trees is often more resilient to adverse weather conditions than annual crops, forest foods often provide a safety net during periods of food shortages caused by crop failure; forest foods also make important contributions during seasonal crop production gaps.
Which one of the following statements best reflects the most logical and rational message conveyed by the author of the passage ?
Answer (d) & explanation
The message is that agroecosystems should be developed along with conventional agriculture (d). Step 1: the passage says sourcing food from forests, wetlands and pastures "in addition to agricultural lands" helps communities all year. Step 2: forest foods act as a safety net when crops fail. They supplement farming, not replace it. That is (d). Step 3: option (a) says food trees should replace other trees, and option (b) says conventional farming cannot ensure food security; both overreach. Option (c), converting wastelands, is not mentioned.
Tip: "in addition to" is the key phrase. Reject options that turn "addition" into "replacement".
Answer as per the official UPSC answer key.
Consider the following trees :
- 1. Jackfruit (*Artocarpus heterophyllus*)
- 2. Mahua (*Madhuca indica*)
- 3. Teak (*Tectona grandis*)
How many of the above are deciduous trees?
Answer (b) & explanation
Two of the three are deciduous (b). A deciduous tree sheds all its leaves in one season, usually the dry summer, to save water. Teak (Tectona grandis) does this; it is the classic tree of India's tropical moist deciduous forests and is prized for its timber. Mahua (Madhuca indica) also sheds its leaves before flowering in spring; its sweet flowers are vital to tribal food and liquor. Item 1 is wrong: jackfruit (Artocarpus heterophyllus) is an evergreen tree of the wetter tracts, such as Kerala's home gardens.
Notice that tropical deciduous forests, also called monsoon forests, are India's most widespread type. Sal, sandalwood, khair and shisham also belong to this group.
Answer as per the official UPSC answer key.
Consider the following organizations/bodies in India :
- 1. The National Commission for Backward Classes
- 2. The National Human Rights Commission
- 3. The National Law Commission
- 4. The National Consumer Disputes Redressal Commission
How many of the above are constitutional bodies?
Answer (a) & explanation
Only one of them is a constitutional body (a). Item 1 is right: the National Commission for Backward Classes became a constitutional body through the 102nd Amendment (2018), which added Article 338B. Item 2 is wrong: the National Human Rights Commission is a statutory body under the Protection of Human Rights Act, 1993. Item 3 is wrong: the Law Commission is set up by a government order for a fixed term, so it is neither constitutional nor statutory. Item 4 is wrong: the NCDRC is a statutory body under consumer protection law, now the Consumer Protection Act, 2019.
Notice the other constitutional commissions: NCSC (Article 338) and NCST (Article 338A). The 22nd Law Commission was led by Justice Ritu Raj Awasthi.
NCBC was statutory (1993) before 2018. Old notes still call it statutory.
Answer as per the official UPSC answer key.
Consider the following activities :
- 1. Spreading finely ground basalt rock on farmlands extensively
- 2. Increasing the alkalinity of oceans by adding lime
- 3. Capturing carbon dioxide released by various industries and pumping it into abandoned subterranean mines in the form of carbonated waters
How many of the above activities are often considered and discussed for carbon capture and sequestration?
Answer (c) & explanation
All three activities are discussed for carbon removal (c). Item 1 is right: enhanced rock weathering: finely ground basalt spread on farms reacts with CO₂ in rain and soil and locks it in stable carbonates; it can also improve soil. Item 2 is right: ocean alkalinity enhancement: adding lime makes seawater more alkaline, so it absorbs more CO₂ from the air. Item 3 is right: pumping captured CO₂ underground as carbonated water is geological storage; in Iceland, the CarbFix project turns it into rock within two years.
Notice that these are carbon dioxide removal methods, needed to reach net zero, alongside cutting emissions. India's Deccan basalts make enhanced rock weathering an attractive option here.
Answer as per the official UPSC answer key.