UPSC Prelims 2025 Science and Technology questions: topic-wise weightage
UPSC Prelims 2025 asked 12 science and technology questions in GS Paper I, spread over 3 topics. See the science and technology weightage for 2025 below, then attempt each question with the official answer and an explanation.
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Science and Technology 2025: questions by topic
- Biology, health and biotechnology3
- Space technology4
- Physics and chemistry in daily life; energy and nuclear technology5
Counted from the 12 questions on this page, tagged by topic in the Battle IAS PYQ bank.
Seeing 12 Science and Technology questions spread over 3 topics can feel overwhelming. That's exactly why the Battle IAS PYQ Book maps every question topic by topic, so you know what to study first. Download free sample
Biology, health and biotechnology 3
Consider the following pairs :
| Plant | Description
| I. Cassava | Woody shrub
| II. Ginger | Herb with pseudostem
| III. Malabar spinach | Herbaceous climber
| IV. Mint | Annual shrub
| V. Papaya | Woody shrub
How many of the above pairs are correctly matched?
Answer (b) & explanation
Three pairs are correctly matched (b). Pair I is right: cassava is a woody shrub grown for its starchy roots. Pair II is right: ginger is a herb whose leafy "stem" is a pseudostem of rolled leaf sheaths above the rhizome. Pair III is right: Malabar spinach is a soft, herbaceous climber. Pair IV is wrong: mint is a perennial herb, not an annual shrub. Pair V is wrong: papaya is a soft-stemmed, tree-like plant, not a woody shrub.
Notice the term pseudostem: the banana plant also has one, which is why it is a giant herb, not a tree. Cassava, also called tapioca, is a major crop in Kerala and a staple food across Africa.
Answer as per the official UPSC answer key.
With reference to monoclonal antibodies, often mentioned in news, consider the following statements :
- I. They are man-made proteins.
- II. They stimulate immunological function due to their ability to bind to specific antigens.
- III. They are used in treating viral infections like that of Nipah virus.
Which of the statements given above are correct?
Answer (d) & explanation
All three statements are correct (d). Statement I is right: monoclonal antibodies are man-made proteins, lab-made copies of one antibody. Statement II is right: each binds one specific antigen, marking the target for the immune system or blocking it. Statement III is right: they are used against viral infections; Kerala has used the monoclonal antibody m102.4 against Nipah under compassionate use. So options (a), (b) and (c) fail.
Notice their wide use: in cancer (such as trastuzumab for breast cancer), autoimmune diseases, and COVID-19. They are costly, so making biosimilars at home is a goal of India's biotech policy. The method of making them, hybridoma, won the 1984 Nobel Prize.
Answer as per the official UPSC answer key.
Consider the following statements :
- I. No virus can survive in ocean waters.
- II. No virus can infect bacteria.
- III. No virus can change the cellular transcriptional activity in host cells.
How many of the statements given above are correct?
Answer (d) & explanation
None of the statements is correct (d). Each "no virus" statement is false. Statement I is wrong: seawater is full of viruses, millions in every millilitre; they kill much of the plankton daily and recycle nutrients. Statement II is wrong: bacteriophages are viruses that infect bacteria. Statement III is wrong: viruses routinely take over the host's transcription machinery to make their own proteins. So options (a), (b) and (c) fail.
Notice the medical use of phages: phage therapy is being tried against antibiotic-resistant bacteria, a growing threat called AMR. Viruses are not truly alive outside a host cell. Some viruses, like HPV, can even cause cancer by changing how host genes are switched on.
Answer as per the official UPSC answer key.
Space technology 4
With reference to Unmanned Aerial Vehicles (UAVs), consider the following statements :
- I. All types of UAVs can do vertical landing.
- II. All types of UAVs can do automated hovering.
- III. All types of UAVs can use battery only as a source of power supply.
How many of the statements given above are correct?
Answer (d) & explanation
None of the statements is correct (d). Each statement says "all types", which is the trap. Statement I is wrong: multi-rotor drones land vertically, but fixed-wing UAVs, such as most military drones, need a runway or a net. Statement II is wrong: fixed-wing UAVs cannot hover; they must keep moving forward. Statement III is wrong: large UAVs run on fuel engines, and some use solar power or hydrogen. So options (a), (b) and (c) fail.
Notice India's drone push: the Drone Rules, 2021, the PLI scheme for drones, and Namo Drone Didi, giving drones to women's self-help groups for spraying crops. India is buying US MQ-9B drones, and drones were widely used in Operation Sindoor (2025).
"All types" in every statement is the clue. One counter-example, the fixed-wing drone, breaks all three.
Answer as per the official UPSC answer key.
Consider the following statements :
- I. It is expected that Majorana 1 chip will enable quantum computing.
- II. Majorana 1 chip has been introduced by Amazon Web Services (AWS).
- III. Deep learning is a subset of machine learning.
Which of the statements given above are correct?
Answer (c) & explanation
Statements I and III are correct (c). Statement I is right: Majorana 1 (February 2025) is a quantum chip built on "topological" qubits, expected to make quantum computing more stable. Statement III is right: deep learning, which uses many-layered neural networks, is a subset of machine learning, itself part of AI. Statement II is wrong: Majorana 1 is Microsoft's chip; Amazon's quantum chip is called Ocelot. So options (a), (b) and (d) fail.
Notice Google's quantum chip, Willow (2024). India's National Quantum Mission (2023) aims to build quantum computers with 50–1,000 qubits. A qubit can be 0 and 1 at once (superposition), which gives quantum computers their power.
Big tech firms announced quantum chips within weeks of each other in 2025: Microsoft (Majorana 1), Amazon (Ocelot) and Google (Willow).
Answer as per the official UPSC answer key.
Consider the following space missions :
- I. Axiom-4
- II. SpaDeX
- III. Gaganyaan
How many of the space missions given above encourage and support micro-gravity research?
Answer (b) & explanation
Two of the missions support microgravity research (b). Item I is right: Axiom-4 (2025) took Shubhanshu Shukla to the International Space Station, where he ran Indian microgravity experiments, such as on sprouting seeds and muscle loss. Item III is right: Gaganyaan is designed to carry microgravity experiments on its crewed and uncrewed flights. Item II is not counted in UPSC's key: SpaDeX was a docking technology demonstration, though it did carry some small payloads.
Notice SpaDeX's importance: in January 2025 India became the fourth country to dock two satellites in space, after the USA, Russia and China. Docking is needed for the planned Bharatiya Antariksh Station and the Chandrayaan-4 sample return.
Answer as per the official UPSC answer key.
GPS-Aided Geo Augmented Navigation (GAGAN) uses a system of ground stations to provide necessary augmentation. Which of the following statements is/are correct in respect of GAGAN?
- I. It is designed to provide additional accuracy and integrity.
- II. It will allow more uniform and high quality air traffic management.
- III. It will provide benefits only in aviation but not in other modes of transportation.
Select the correct answer using the code given below.
Answer (d) & explanation
Statements I and II are correct (d). GAGAN, built by ISRO and the Airports Authority of India, corrects GPS signals using ground stations and geostationary satellites. Statement I is right: it adds accuracy and integrity. Statement II is right: it allows more uniform, high-quality air traffic management and safer aircraft approaches. Statement III is wrong: its signal is also used for railways, shipping, fishing alerts and surveying. So options (a), (b) and (c) fail.
Notice the difference: GAGAN improves GPS, while NavIC (IRNSS) is India's own independent regional navigation system. India was the third country, after the USA and Europe, with such an aviation-grade satellite-based augmentation system.
Answer as per the official UPSC answer key.
Physics and chemistry in daily life; energy and nuclear technology 5
Consider the following types of vehicles :
- I. Full battery electric vehicles
- II. Hydrogen fuel cell vehicles
- III. Fuel cell-electric hybrid vehicles
How many of the above are considered as alternative powertrain vehicles?
Answer (c) & explanation
All three are alternative powertrain vehicles (c). An alternative powertrain is any drive system other than the conventional petrol or diesel engine. Item I is right: full battery electric vehicles run only on a battery and motor. Item II is right: hydrogen fuel cell vehicles make electricity from hydrogen. Item III is right: fuel cell–electric hybrid vehicles combine a fuel cell with a battery. So options (a), (b) and (d) fail. CNG and petrol-electric hybrid cars also count.
Notice India's push: the PM E-DRIVE scheme (2024) for electric vehicles, FAME before it, and the National Green Hydrogen Mission (2023). Flex-fuel cars running on ethanol blends are another option, with E20 petrol now sold across India.
Answer as per the official UPSC answer key.
In the context of electric vehicle batteries, consider the following elements :
- I. Cobalt
- II. Graphite
- III. Lithium
- IV. Nickel
How many of the above usually make up battery cathodes?
Answer (c) & explanation
Three of the four usually make up cathodes (c). A lithium-ion cathode is a lithium metal oxide, such as nickel-manganese-cobalt (NMC), nickel-cobalt-aluminium (NCA), or lithium iron phosphate (LFP). So lithium (III), nickel (IV) and cobalt (I) go into cathodes. Item II is wrong: graphite is the usual anode material, not the cathode. So options (a), (b) and (d) fail.
Notice the shift to LFP batteries, which avoid costly cobalt and are safer, now common in EVs. Sodium-ion batteries are an emerging cheaper option. India's PLI scheme for Advanced Chemistry Cell batteries aims to make cells at home, and the Kolar and Jammu lithium finds made news.
Answer as per the official UPSC answer key.
Consider the following substances :
- I. Ethanol
- II. Nitroglycerine
- III. Urea
Coal gasification technology can be used in the production of how many of them?
Answer (b) & explanation
Coal gasification can produce two of them (b). Gasification turns coal into syngas, a mix of carbon monoxide and hydrogen. Item III is right: syngas can be made into ammonia and then urea, as at the revived Talcher fertiliser plant. Item I is right: syngas can be made into methanol and ethanol, which is why India's coal gasification mission names these products. Item II is wrong: nitroglycerine is made by nitrating glycerol, which comes from fats, not from syngas.
Notice the National Coal Gasification Mission, aiming to gasify 100 million tonnes of coal by 2030, to cut imports of gas, ammonia and methanol. Gasification is cleaner than burning coal directly, but still emits CO₂.
Answer as per the official UPSC answer key.
What is the common characteristic of the chemical substances generally known as CL-20, HMX and LLM-105, which are sometimes talked about in media?
Answer (b) & explanation
They are explosives used in military weapons (b). CL-20 (hexanitrohexaazaisowurtzitane), HMX (octogen) and LLM-105 are high explosives used in warheads and munitions. CL-20 is among the most powerful non-nuclear explosives. LLM-105 is valued because it is insensitive, so it does not go off easily by accident. Option (a) is wrong: they are not refrigerants. Options (c) and (d) are wrong: they are not fuels for cruise missiles or rockets, which burn steadily rather than detonate.
Notice India's interest: DRDO's High Energy Materials Research Laboratory in Pune works on such compounds. Other common military explosives include RDX and TNT. Some rocket propellants do add HMX for extra energy.
Answer as per the official UPSC answer key.
Consider the following statements :
Statement I : Some rare earth elements are used in the manufacture of flat television screens and computer monitors.
Statement II : Some rare earth elements have phosphorescent properties.
Which one of the following is correct in respect of the above statements?
Answer (a) & explanation
Both are correct and Statement II explains Statement I (a). Statement I is right: some rare earth elements are used in flat TV screens and monitors. Statement II is right and is the reason: rare earths such as europium, terbium and yttrium are used as phosphors, the materials that glow red, green and blue in screens and LED lighting. Their light-giving property is why screens use them. So options (b), (c) and (d) fail.
Notice their other uses: neodymium magnets in EV motors and wind turbines. China controls most rare earth processing, and its export curbs in 2025 hit carmakers worldwide. India's IREL mines rare earths from beach sands in Kerala and Odisha, and a 2025 scheme backs rare-earth magnet making.
Answer as per the official UPSC answer key.
All years by topic
Every question from 2011 to 2026, grouped by syllabus topic, with year-wise trends.