Science PYQs topic-wise

Question 1

Which of the following statements with regard to India’s Deep Ocean Mission is/are correct?
1. It was launched by the Ministry of Ports, Shipping and Waterways, Government of India.
2. Matsya-6000 has been designed to carry 3 people for deep sea exploration.
3. Samudrayaan is a project under this mission.
Select the answer using the code given below: (A) 1 only (B) 2 and 3 only (C) 1 and 2 only (D) 1, 2 and 3

Accepted Answer

(B) 2 and 3 only — UPSC provisional key: (B), Series A question 50. Statements 2 and 3 are correct. MATSYA-6000 is designed for a three-person crew and is being developed through Samudrayaan under the Deep Ocean Mission. Statement 1 is false because the responsible ministry is Earth Sciences, with NIOT developing the submersible. Sources: [UPSC provisional answer key]() · [Ministry of Earth Sciences: Samudrayaan Project, July 2023]() · [ISRO: Personnel sphere for Samudrayaan, three-member crew]()

Question 2

Which of the following statements with regard to GenomeIndia Project is/are correct?
1. It is a part of the Human Genome Project.
2. The project is funded by the Department of Biotechnology (DBT), Government of India.
3. Its primary aim is to build a catalogue of genetic diversity of the Indian population.
Select the answer using the code given below: (A) 1 only (B) 2 and 3 only (C) 1 and 2 only (D) 1, 2 and 3

Accepted Answer

(B) 2 and 3 only — UPSC provisional key: (B), Series A question 48. Statements 2 and 3 are correct. DBT sanctioned GenomeIndia to study genetic variation across Indian populations, addressing diversity that a single reference genome cannot represent. It is distinct from the earlier international Human Genome Project, so statement 1 is false. Sources: [UPSC provisional answer key]() · [PIB/DBT: GenomeIndia—Cataloguing the Genetic Variation in Indians, 2020]() · [Indian Biological Data Centre: GenomeIndia]()

Question 3

Which of the following statements with regard to stealth technology is/are correct?
1. Stealth objects have a very small radar cross-section and are coated with Radar Absorbing Material.
2. Stealth objects can be detected using specific frequencies.
3. Stealth objects are coated with metamaterials to increase the scattering of electromagnetic radiation.
Select the answer using the code given below: (A) 1 only (B) 2 and 3 only (C) 1 and 2 only (D) 1, 2 and 3

Accepted Answer

(C) 1 and 2 only — UPSC provisional key: (C), Series A question 43. Statements 1 and 2 are correct in the question’s framework. Radar-absorbing materials and shaping reduce the returned signal, but their effectiveness depends on frequency, geometry and viewing direction, so stealth does not mean universal invisibility. Statement 3 is misleading because increased radar backscatter would work against low observability. Sources: [UPSC provisional answer key]() · [DRDO: Stealth, Camouflage and Countermeasure Technologies, January–February 2024]() · [DRDO: Materials technology priorities and radar cross-section reduction]()

Question 4

Which of the following statements with regard to Large Language Models (LLMs) used in machine learning is/are correct?
1. LLMs assign probabilities to the next possible words and then pick the one with the highest probability.
2. LLMs process data through mathematical optimization to minimise prediction errors.
3. LLMs produce unbiased outputs.
Select the answer using the code given below: (A) 1 only (B) 1 and 2 only (C) 2 and 3 only (D) 1, 2 and 3

Accepted Answer

(B) 1 and 2 only — UPSC provisional key: (B), Series A question 42. UPSC accepts statements 1 and 2. Training adjusts model parameters to reduce prediction loss, and greedy decoding chooses the highest-probability next token. However, this is not how every LLM output is generated: sampling can choose other tokens. Statement 3 is false because training data, model design and use can produce biased outputs. Sources: [UPSC provisional answer key]() · [Hugging Face Transformers: Generation strategies, greedy decoding and sampling]() · [OpenAI GPT-2 model card: language modelling and bias limitations]()

Question 5

Consider the following statements with regard to involvement of private entities in India’s space programme:
1. The Indian National Space Promotion and Authorisation Centre (IN-SPACe) is an autonomous agency formed to facilitate participation of private entities.
2. Agnikul Cosmos launched the world’s first flight using 3D-printed rocket engine.
3. Skyroot Aerospace has developed liquid fuel for GSLV.
Which of the statements given above is/are correct? (A) 1 only (B) 2 and 3 only (C) 1 and 2 only (D) 1, 2 and 3

Accepted Answer

(C) 1 and 2 only — UPSC provisional key: (C), Series A question 46. Statements 1 and 2 are accepted. IN-SPACe facilitates private participation, and Agnikul flew Agnibaan SOrTeD with a single-piece 3D-printed engine in May 2024. That single-piece qualifier matters: this was not the first rocket ever to use any 3D-printed engine components. Statement 3 is not the Skyroot achievement identified by official sources. Sources: [UPSC provisional answer key]() · [PIB: Agnikul launches rocket with fully 3D-printed engine, 30 May 2024]() · [ISRO: Mission Prarambh and Skyroot Vikram-S]() · [IN-SPACe: autonomous agency role and private-sector participation]()

Question 6

Which of the following statements with regard to drone swarms is/are correct?
1. They use Terahertz band of frequency to communicate with the command centre.
2. Individual drones in the swarm can communicate with other drones in the swarm.
3. GPS Spoofing is a commonly used technique to counter drone swarm attack.
Select the answer using the code given below: (A) 1 only (B) 2 and 3 only (C) 1 and 2 only (D) 1, 2 and 3

Accepted Answer

(B) 2 and 3 only — UPSC provisional key: (B), Series A question 47. UPSC accepts statements 2 and 3. Swarm members can exchange information for coordination, and spoofing can mislead drones that rely on vulnerable satellite-navigation signals. This is not a universal defence: autonomous navigation, resilient receivers or alternative positioning can reduce that vulnerability. Statement 1’s terahertz requirement is not a general feature of swarms. Sources: [UPSC provisional answer key]() · [Primary research: GPS-Spoofing Attack Detection Mechanism for UAV Swarms]() · [Primary research: Detection and Mitigation of Position Spoofing Attacks on Cooperative UAV Swarm Formations]()

Question 7

Which of the following statements with regard to Green Hydrogen is/are correct?
1. It is decarbonized hydrogen obtained from natural gas reforming combined with carbon capture and storage (CCS).
2. It is produced using electrolysis of water with electricity generated by renewable energy.
3. National Green Hydrogen Mission of India aims for abatement of nearly 50 MMT of annual greenhouse gas emissions by 2030.
Select the answer using the code given below: (A) 1 only (B) 2 and 3 only (C) 2 only (D) 1, 2 and 3

Accepted Answer

(B) 2 and 3 only — UPSC provisional key: (B), Series A question 45. Statements 2 and 3 are correct. Renewable electricity can split water into hydrogen and oxygen, and the National Green Hydrogen Mission projects annual greenhouse-gas abatement of nearly 50 million metric tonnes by 2030. Statement 1 describes a different production route, commonly called blue hydrogen. Sources: [UPSC provisional answer key]() · [PIB: National Green Hydrogen Mission outcomes, February 2026]() · [MNRE: National Green Hydrogen Mission production pathways]() · [MNRE-hosted Andhra Pradesh policy: hydrogen production route definitions]()

Question 8

Which of the following statements regarding the features of blockchain technology are correct?
1. Records stored in the database may be made visible to relevant stakeholders without risk of alteration.
2. Copies of the entire database are stored on multiple computers on a network, syncing within seconds.
3. Consortium blockchain is a blend of public and private blockchains allowing selective data access.
4. Mathematical algorithms make it impossible to change or delete any data once recorded and accepted.
Select the answer using the code given below: (A) 1 and 3 (B) 2 and 4 only (C) 1, 2 and 4 (D) 1 and 4 only

Accepted Answer

(C) 1, 2 and 4 — UPSC provisional key: (C), Series A question 86. The provisional key selects 1, 2 and 4 and excludes the consortium/hybrid confusion in 3. Technically, NIST calls blockchains tamper-evident and tamper-resistant, not absolutely immutable: finality, replication speed and stored history vary by network, and attacks, forks or agreed rule changes can alter outcomes. Sources: [UPSC provisional answer key]() · [NISTIR 8202: Blockchain Technology Overview, especially section 7.1]() · [NIST: distributed ledgers, cryptographic links and consensus]() · [National Informatics Centre: consortium and hybrid blockchain types]()

Question 9

Which of the following statements with regard to genetic medicine is/are correct?
1. Genetic medicines correct/compensate for the faulty genes responsible for disease.
2. Engineered viruses and lipid nanoparticles are used as carriers of the genetic medicine.
3. Genetic medicines alter the entire DNA sequence.
Select the answer using the code given below: (A) 1 only (B) 2 and 3 only (C) 1 and 2 only (D) 1, 2 and 3

Accepted Answer

(C) 1 and 2 only — UPSC provisional key: (C), Series A question 41. Statements 1 and 2 are correct. Gene transfer may supply a functional gene, while editing can alter a selected DNA target; viral vectors and lipid nanoparticles are delivery approaches. The intervention is targeted, so statement 3’s claim about altering the entire DNA sequence is false. Sources: [UPSC provisional answer key]() · [NIH NHLBI: Types of genetic therapies]() · [NIH NHLBI: Gene-therapy delivery research workshop]()

Question 10

Which of the following statements with regard to Black Boxes used in modern aircrafts is/are correct?
1. They carry a beacon emitting red light pulses to facilitate underwater detection.
2. They record both the cockpit voice and flight data.
3. Their memory units are made using either stainless steel or titanium.
Select the answer using the code given below: (A) 1 only (B) 2 and 3 only (C) 1 and 2 only (D) 1, 2 and 3

Accepted Answer

(B) 2 and 3 only — UPSC provisional key: (B), Series A question 44. Statements 2 and 3 are accepted. The cockpit voice recorder captures cockpit sound while the flight data recorder stores flight parameters. Stainless steel or titanium protects the crash-survivable memory assembly; the electronic memory chips themselves are not made of those metals. Statement 1 confuses an acoustic underwater beacon with a light. Sources: [UPSC provisional answer key]() · [NTSB: Cockpit Voice Recorders and Flight Data Recorders]() · [Curtiss-Wright: How flight recorders survive aircraft accidents]()

Question 11

Which of the following statements with regard to the National Quantum Mission (NQM) is/are correct?
1. It aims at developing intermediate-scale quantum computers with 50-1000 physical qubits.
2. Its implementation includes setting up of four Thematic Hubs (T-Hubs) in academic and national R&D institutes across India.
Select the answer using the code given below: (A) 1 only (B) 2 only (C) Both 1 and 2 (D) Neither 1 nor 2

Accepted Answer

(C) Both 1 and 2 — UPSC provisional key: (C), Series A question 49. Both statements are correct. DST lists development of intermediate-scale computers with 50–1,000 physical qubits and four hubs for quantum computing, communication, sensing and metrology, and materials and devices. These are mission objectives and organisational arrangements, not a claim that every target machine is already operational. Sources: [UPSC provisional answer key]() · [DST: National Quantum Mission objectives and thematic hubs]()

Question 12

Consider the following substances:
1. Ethanol
2. Nitroglycerine
3. Urea
Coal gasification technology can be used in the production of how many of them? (A) Only one (B) Only two (C) All three (D) None

Accepted Answer

(C) All three — Correct. Coal gasification yields synthesis gas, which can be catalytically converted to ethanol, used to produce ammonia for urea, and processed into nitroglycerine precursors.

Question 13

With reference to Unmanned Aerial Vehicles (UAVs), consider the following statements:
1. All types of UAVs can do vertical landing.
2. All types of UAVs can do automated hovering.
3. All types of UAVs can use battery only as a source of power supply.
How many of the statements given above are correct? (A) Only one (B) Only two (C) All three (D) None

Accepted Answer

(D) None — Correct. Fixed-wing UAVs cannot do vertical landing or automated hovering, and many UAVs use internal combustion engines or hybrid power, not batteries alone.

Question 14

Consider the following statements:
1. No virus can survive in ocean waters.
2. No virus can infect bacteria.
3. No virus can change the cellular transcriptional activity in host cells.
Which of the statements given above are correct? (A) Only one (B) Only two (C) All three (D) None

Accepted Answer

(D) None — Correct. Marine viruses (bacteriophages) thrive in oceans; bacteriophages specifically infect bacteria; and many viruses alter host cell transcription by hijacking cellular machinery.

Question 15

Consider the following space missions:
1. Axiom-4
2. SpaDeX
3. Gaganyaan
How many of the space missions given above encourage and support micro-gravity research? (A) Only one (B) Only two (C) All three (D) None

Accepted Answer

(C) All three — Correct. Axiom-4 conducts micro-gravity experiments on the ISS, SpaDeX demonstrates docking for future space station modules, and Gaganyaan is India's crewed mission with micro-gravity research payloads.

Question 16

Consider the following statements:
1. It is expected that Majorana 1 chip will enable quantum computing.
2. Majorana 1 chip has been introduced by Amazon Web Services (AWS).
3. Deep learning is a subset of machine learning.
Which of the statements given above are correct? (A) 1 and 2 only (B) 2 and 3 only (C) 1 and 3 only (D) 1, 2 and 3

Accepted Answer

(C) 1 and 3 only — Correct. The Majorana 1 chip, developed by Microsoft, is designed to advance quantum computing using topological qubits. Deep learning is indeed a subset of machine learning that uses multi-layered neural networks.

Question 17

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? (A) Both Statement-I and Statement-II are correct and Statement-II explains Statement-I (B) Both Statement-I and Statement-II are correct but Statement-II does not explain Statement-I (C) Statement-I is correct but Statement-II is not correct (D) Statement-I is not correct but Statement-II is correct

Accepted Answer

(A) Both Statement-I and Statement-II are correct and Statement-II explains Statement-I — Correct. Rare earth elements like europium and terbium are used in display phosphors. Their phosphorescent properties are the reason they are employed in screens and monitors.

Question 18

In the context of electric vehicle batteries, consider the following elements:
1. Cobalt
2. Graphite
3. Lithium
4. Nickel
How many of the above usually make up battery cathodes? (A) Only one (B) Only two (C) Only three (D) All the four

Accepted Answer

(C) Only three — Correct. Cobalt, lithium and nickel are standard cathode components in Li-ion batteries. Graphite is used as the anode material, not the cathode.

Question 19

Consider the following statements:
1. Indian Railways have prepared a National Rail Plan (NRP) to create a future ready railway system by 2028.
2. 'Kavach' is an Automatic Train Protection system developed in collaboration with Germany.
3. 'Kavach' system consists of RFID tags fitted on track in station section.
Which of the statements given above are not correct? (A) 1 and 2 only (B) 2 and 3 only (C) 1 and 3 only (D) 1, 2 and 3

Accepted Answer

(A) 1 and 2 only — Correct. The NRP target year is 2030, not 2028, and Kavach was developed indigenously by RDSO (Research Designs and Standards Organisation), not with Germany.

Question 20

Consider the following statements:
Statement-I: Giant stars live much longer than dwarf stars.
Statement-II: Compared to dwarf stars, giant stars have a greater rate of nuclear reactions.
Which one of the following is correct in respect of the above statements? (A) Both Statement-I and Statement-II are correct and Statement-II explains Statement-I (B) Both Statement-I and Statement-II are correct, but Statement-II does not explain Statement-I (C) Statement-I is correct, but Statement-II is incorrect (D) Statement-I is incorrect, but Statement-II is correct

Accepted Answer

(D) Statement-I is incorrect, but Statement-II is correct — Correct. Giant stars have higher nuclear reaction rates (Statement-II is true) but this causes them to exhaust fuel faster, giving them shorter, not longer, lifespans (Statement-I is false).

Question 21

Which one of the following words/phrases is most appropriately used to denote "an interoperable network of 3D virtual worlds that can be accessed simultaneously by millions of users, who can exert property rights over virtual items"? (A) Big data analytics (B) Cryptography (C) Metaverse (D) Virtual matrix

Accepted Answer

(C) Metaverse — Correct. The Metaverse describes an interoperable network of persistent 3D virtual worlds where users can interact, own virtual property, and conduct transactions.

Question 22

Which one of the following is synthesised in human body that dilates blood vessels and increases blood flow? (A) Nitric oxide (B) Nitrous oxide (C) Nitrogen dioxide (D) Nitrogen pentoxide

Accepted Answer

(A) Nitric oxide — Correct. Nitric oxide (NO) is produced by endothelial cells lining blood vessels and acts as a vasodilator, relaxing smooth muscle and increasing blood flow.

Question 23

Consider the following activities:
1. Identification of narcotics on passengers at airports or in aircraft
2. Monitoring of precipitation
3. Tracking the migration of animals
In how many of the above activities can radars be used? (A) Only one (B) Only two (C) All three (D) None

Accepted Answer

(C) All three — Correct. Millimetre-wave scanners (a radar type) detect concealed substances at airports, weather radars monitor precipitation, and Doppler radars track animal migration patterns.

Question 24

In which of the following are hydrogels used?
1. Controlled drug delivery in patients
2. Mobile air-conditioning systems
3. Preparation of industrial lubricants
Select the correct answer using the code given below: (A) 1 only (B) 1 and 2 only (C) 2 and 3 only (D) 1, 2 and 3

Accepted Answer

(D) 1, 2 and 3 — Correct. Hydrogels are used in drug delivery (controlled release matrices), air-conditioning systems (desiccant cooling), and as bases for industrial lubricants.

Question 25

With reference to radioisotope thermoelectric generators (RTGs), consider the following statements:
1. RTGs are miniature fission reactors.
2. RTGs are used for powering the onboard systems of spacecrafts.
3. RTGs can use Plutonium-238, which is a by-product of weapons development.
Which of the statements given above are correct? (A) 1 and 2 only (B) 2 and 3 only (C) 1 and 3 only (D) 1, 2 and 3

Accepted Answer

(B) 2 and 3 only — Correct. RTGs rely on radioactive decay (not fission) to generate electricity for spacecraft, and they commonly use Plutonium-238 originally produced in weapons-grade reactor programmes.

Science PYQs topic-wise — UPSC Prelims

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Physics in Everyday Life	41	2026
Chemistry in Everyday Life	44	2025
Cell Biology and Genetics	23	2025
Human Physiology	14	2024
Plant Biology and Applied Biology	11	2018
Disease, Immunity and Public Health	14	2023
Biotechnology	32	2026
Space Science and Astronomy	45	2026
Computers, ICT and Emerging Tech	36	2026
Energy, Nuclear and Material Science	11	2026
Robotics, AI and Advanced Technology	4	2026
Science Institutions, Missions and Applications	1	2026
General Science Mixed Concepts	38	2023