Science and Technology PYQs for UPSC Prelims 2027: 100 Inevitable Questions & Answers

Introduction

Science and Technology PYQs for UPSC Prelims are an important resource for understanding how the UPSC Civil Services Preliminary Examination tests scientific concepts, emerging technologies and their real-world applications.

Science and Technology questions in UPSC Prelims are generally not limited to simple factual recall. They often require candidates to understand a scientific concept, identify its application, evaluate multiple statements and connect current developments with basic science. Topics such as biotechnology, space technology, artificial intelligence, digital technologies, energy, electric vehicles, nuclear technology, health, genetics and materials science have appeared in recent examinations.

The official UPSC syllabus includes General Science in General Studies Paper I, while current developments in science and technology can also intersect with the broader current-affairs component of the examination.

This article brings together 100 topic-wise questions covering the major areas of Science and Technology relevant to UPSC Prelims. It also examines the pattern of actual UPSC questions from the 2021–2025 period so that aspirants can understand not only what to study but also how UPSC frames questions.

The Science and Technology PYQs for UPSC Prelims given below are arranged topic-wise to make revision systematic and exam-oriented.

Important Note: The actual UPSC Previous Year Questions (PYQs) should always be verified against the official UPSC question papers. The practice questions in this article are designed in the UPSC CSE Prelims pattern, while clearly identified PYQ-based questions are used to highlight concepts tested by UPSC.

Apart from attempting advanced Science and Technology PYQs for UPSC Prelims, aspirants should build a strong foundation in the basic concepts and understand the overall syllabus. For a broader preparation framework, read our detailed guide on Science and Technology for UPSC Prelims 2027.

Section 1: Biotechnology, Genetics & Health — 20 MCQs

This collection of Science and Technology PYQs for UPSC Prelims covers major areas such as biotechnology, space technology, artificial intelligence, energy, environment and emerging technologies.

Q.1. With reference to CRISPR-Cas9 technology, consider the following statements:

1. CRISPR sequences are associated with a defence mechanism found naturally in certain microorganisms.
2. Cas9 is an enzyme capable of cutting DNA at a targeted location.
3. CRISPR-Cas9 can be used only for modifying plant genomes.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.2. With reference to messenger RNA (mRNA) vaccines, consider the following statements:

1. They introduce genetic instructions that enable cells to produce a specific antigen.
2. The mRNA necessarily becomes integrated into the recipient’s nuclear DNA.
3. The antigen produced following vaccination can stimulate an immune response.

Which of the statements given above are correct?

(a) 1 and 3 only
(b) 2 only
(c) 1 and 2 only
(d) 1, 2 and 3

Q.3. Consider the following statements regarding stem cells:

1. Stem cells can undergo self-renewal.
2. Some stem cells can differentiate into specialized cell types.
3. All stem cells are obtained only from embryos.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.4. With reference to genetically modified organisms, consider the following statements:

1. Genetic modification may involve introducing a gene from another organism.
2. Every genetically modified crop is necessarily resistant to insects.
3. Genetic modification can be used to alter nutritional characteristics.

Which of the statements given above are correct?

(a) 1 and 3 only
(b) 2 only
(c) 1 and 2 only
(d) 1, 2 and 3

Q.5. Consider the following pairs:

Which of the pairs given above are correctly matched?

(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.6. With reference to DNA barcoding, consider the following statements:

1. It can help distinguish closely related species.
2. It can have applications in identifying adulteration in biological products.
3. It necessarily determines the age of an organism.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 only
(d) 1, 2 and 3

Q.7. Consider the following statements regarding monoclonal antibodies:

1. They are designed to recognize a specific antigen.
2. They can have diagnostic as well as therapeutic applications.
3. They are produced only by naturally occurring immune responses.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.8. Which one of the following best describes a vector in genetic engineering?

(a) A molecule that destroys all foreign DNA
(b) A carrier used to introduce genetic material into a host cell
(c) A protein that permanently prevents DNA replication
(d) A microorganism incapable of carrying genetic material

Q.9. With reference to gene editing, consider the following statements:

1. It can involve targeted changes to DNA sequences.
2. It can potentially be used in medical research.
3. It necessarily changes every cell of an organism.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 1 only
(c) 2 and 3 only
(d) 1, 2 and 3

Q.10. Consider the following organisms:

1. Bacteria
2. Archaea
3. Fungi

Which of the above can be used in biotechnology for industrial or pharmaceutical applications?

(a) 1 only
(b) 1 and 2 only
(c) 2 and 3 only
(d) 1, 2 and 3

Q.11. With reference to probiotics, consider the following statements:

1. They are living microorganisms that may provide health benefits when consumed in adequate amounts.
2. All probiotics are pathogenic microorganisms.
3. Some probiotic microorganisms are bacteria.

Which of the statements given above are correct?

(a) 1 and 3 only
(b) 2 only
(c) 1 and 2 only
(d) 1, 2 and 3

Q.12. Which one of the following is most directly associated with the production of recombinant proteins?

(a) Recombinant DNA technology
(b) Nuclear fission
(c) Radioactive decay
(d) Optical fibre communication

Q.13. Consider the following statements regarding biofortification:

1. It aims to improve the nutritional quality of food crops.
2. It can involve conventional plant breeding.
3. It necessarily requires genetic modification.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 1 only
(c) 2 and 3 only
(d) 1, 2 and 3

Q.14. With reference to viruses, consider the following statements:

1. Viruses require host cells for replication.
2. Antibiotics are generally effective against viral infections.
3. Viral genetic material may be DNA or RNA.

Which of the statements given above are correct?

(a) 1 and 3 only
(b) 2 only
(c) 1 and 2 only
(d) 1, 2 and 3

Q.15. Consider the following statements about mRNA technology:

1. mRNA carries genetic instructions used in protein synthesis.
2. mRNA vaccines work by introducing a live virus into the body.
3. Cellular machinery can use mRNA to produce a protein.

Which of the statements given above are correct?

(a) 1 and 3 only
(b) 1 and 2 only
(c) 2 and 3 only
(d) 1, 2 and 3

Q.16. Which one of the following pairs is correctly matched?

(a) CRISPR-Cas9 — Targeted genome editing
(b) PCR — Nuclear power generation
(c) mRNA vaccine — Radioactive imaging
(d) Stem cells — Satellite navigation

Q.17. Consider the following statements regarding genetically engineered microorganisms:

1. They can be used for production of pharmaceuticals.
2. They can be used for production of industrial enzymes.
3. Their use is restricted exclusively to agriculture.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 1 only
(c) 2 and 3 only
(d) 1, 2 and 3

Q.18. Which one of the following is an example of a molecular diagnostic technique?

(a) Polymerase Chain Reaction
(b) Conventional ploughing
(c) Satellite imaging
(d) Nuclear reactor cooling

Q.19. Consider the following statements regarding antimicrobial resistance:

1. It can arise when microorganisms evolve mechanisms that reduce the effectiveness of antimicrobial medicines.
2. Misuse and overuse of antimicrobial medicines can contribute to the problem.
3. It is restricted only to bacterial infections.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 1 only
(c) 2 and 3 only
(d) 1, 2 and 3

Q.20. PYQ-based: Recent UPSC questions have tested the ability to connect a scientific term with its real-world application rather than merely define it. Which of the following is the most appropriate association?

(a) ACE2 — receptor involved in cellular entry of certain viruses
(b) CRISPR — satellite navigation system
(c) DNA barcoding — measurement of atmospheric pressure
(d) mRNA — nuclear reactor coolant

Answers — Section 1

1. (a) — CRISPR systems originated as microbial defence mechanisms; Cas9 is a DNA-cutting enzyme.
2. (a) — mRNA supplies instructions for antigen production; it does not normally integrate into nuclear DNA.
3. (a) — Self-renewal and differentiation are defining properties of stem cells; they are not exclusively embryonic.
4. (a) — GM technology can introduce genes and alter traits; not every GM crop is insect-resistant.
5. (d) — All three associations are correct.
6. (a) — DNA barcoding is useful for species identification and biological authentication; it does not necessarily determine age.
7. (a) — Monoclonal antibodies recognize specific targets and have diagnostic and therapeutic uses.
8. (b) — A vector carries genetic material into a host cell.
9. (a) — Gene editing can make targeted DNA changes and has medical applications; it need not affect every cell.
10. (d) — All three groups have biotechnology applications.
11. (a) — Probiotics are beneficial microorganisms when used appropriately; many are bacteria.
12. (a) — Recombinant DNA technology is widely used to produce recombinant proteins.
13. (a) — Biofortification can use conventional breeding as well as biotechnology.
14. (a) — Viruses require host cells and may possess DNA or RNA; antibiotics do not generally treat viruses.
15. (a) — mRNA carries instructions and can be translated into protein; it is not a live virus.
16. (a) — CRISPR-Cas9 is a genome-editing technology.
17. (a) — Engineered microorganisms have pharmaceutical and industrial uses.
18. (a) — PCR amplifies specific DNA sequences and is used in molecular diagnostics.
19. (a) — Resistance is broader than bacterial disease, although bacterial AMR is a major concern.
20. (a) — ACE2 is a cellular receptor associated with entry of SARS-CoV-2 and certain other viruses. A 2021 UPSC question specifically tested ACE2 in the context of viral disease.

By practising Science and Technology PYQs for UPSC Prelims, candidates can identify recurring concepts and understand the changing pattern of questions.

Biotechnology is one of the areas where UPSC frequently connects basic scientific concepts with contemporary developments. Candidates who want to strengthen this area can also refer to our detailed article on Biotechnology and Genetic Engineering for UPSC Prelims.

Section 2: Space Technology, Astronomy & Nuclear Science — 20 MCQs

Q.21. With reference to geostationary satellites, consider the following statements:

1. They orbit over the equator.
2. Their orbital period is approximately equal to Earth’s rotation period.
3. They appear stationary relative to an observer on Earth.

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

Q.22. Consider the following pairs:

Which of the pairs given above are correctly matched?

(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.23. With reference to India’s satellite navigation system, consider the following statements:

1. NavIC is India’s regional satellite navigation system.
2. Navigation satellites can provide positioning and timing services.
3. Satellite navigation requires all satellites to remain stationary over one location on Earth.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 only
(d) 1, 2 and 3

Q.24. Which one of the following is the principal purpose of a launch vehicle?

(a) To place a spacecraft or satellite into a desired trajectory or orbit
(b) To provide permanent electricity to a satellite after launch
(c) To control weather systems
(d) To generate Earth’s magnetic field

Q.25. With reference to cryogenic rocket engines, consider the following statements:

1. They can use liquid hydrogen and liquid oxygen as propellants.
2. Cryogenic propellants are stored at very low temperatures.
3. Cryogenic engines cannot be used for space launch vehicles.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 1 only
(c) 2 and 3 only
(d) 1, 2 and 3

Q.26. Consider the following statements regarding radioisotope thermoelectric generators (RTGs):

1. They can provide electrical power from radioactive decay.
2. They can be useful for spacecraft operating far from the Sun.
3. They are identical to conventional nuclear fission reactors.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 only
(d) 1, 2 and 3

Q.27. PYQ-based: UPSC has tested RTGs in the context of spacecraft power generation. Which of the following best explains why RTGs are useful in deep-space missions?

(a) They generate power from radioactive decay without depending on sunlight.
(b) They generate electricity exclusively through solar panels.
(c) They operate by burning atmospheric oxygen.
(d) They require a terrestrial power grid.

Q.28. Consider the following statements regarding gravitational waves:

1. They are disturbances propagating through spacetime.
2. They can be generated by certain violent astrophysical events.
3. Their detection can provide information about compact astrophysical objects.

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

Q.29. With reference to nuclear fission and fusion, consider the following statements:

1. Nuclear fission involves splitting a heavy atomic nucleus.
2. Nuclear fusion involves combining light nuclei under suitable conditions.
3. The Sun derives its energy primarily from nuclear fusion.

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

Q.30. Which one of the following is most directly associated with a tokamak?

(a) Controlled nuclear fusion research
(b) Satellite navigation
(c) Fibre-optic communication
(d) Semiconductor fabrication

Q.31. Consider the following statements regarding black holes:

1. Their gravitational field can be sufficiently strong that light cannot escape from within the event horizon.
2. They can form from the collapse of sufficiently massive stars.
3. They can be directly observed as ordinary luminous surfaces.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.32. With reference to a light-year, consider the following statements:

1. It is a unit of distance.
2. It represents the distance travelled by light in vacuum in one year.
3. It is a unit of time.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 only
(d) 1, 2 and 3

Q.33. Which one of the following explains why stars of greater mass generally have shorter main-sequence lifetimes than lower-mass stars?

(a) Massive stars consume their nuclear fuel at a much higher rate.
(b) Massive stars contain no hydrogen.
(c) Massive stars do not undergo nuclear reactions.
(d) Massive stars receive less gravitational energy.

Q.34. Consider the following statements about remote sensing satellites:

1. They can collect information about Earth’s surface without direct physical contact.
2. Different wavelengths can reveal different surface characteristics.
3. They are incapable of monitoring vegetation.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.35. With reference to India’s space programme, consider the following statements:

1. Earth-observation satellites have applications in agriculture.
2. Communication satellites can support telecommunications.
3. Space-based systems can assist disaster management.

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

Q.36. Which one of the following is a major advantage of placing an astronomical observatory in space?

(a) Avoidance of much of Earth’s atmospheric interference
(b) Elimination of gravitational force
(c) Complete absence of cosmic radiation
(d) Permanent exposure to sunlight for all instruments

Q.37. Consider the following statements regarding satellites in polar or near-polar orbits:

1. They can pass over or near the polar regions.
2. They are useful for repeated Earth observation.
3. They necessarily remain fixed over one geographical point.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 1 only
(c) 2 and 3 only
(d) 1, 2 and 3

Q.38. Which one of the following is most closely associated with Chandrayaan-type missions?

(a) Lunar exploration
(b) Deep-sea exploration
(c) Atmospheric weather forecasting alone
(d) Subterranean mineral exploration

Q.39. Consider the following statements regarding solar activity:

1. Solar flares can release large amounts of energy.
2. Solar activity can influence space weather.
3. Space weather can affect satellites and communication systems.

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

Q.40. PYQ-based: A recurring UPSC pattern is to ask about the purpose of a space technology rather than its definition. Which of the following is correctly matched?

(a) RTG — electrical power from radioactive decay
(b) NavIC — weather modification
(c) Geostationary orbit — permanent polar coverage
(d) Tokamak — satellite propulsion

Answers — Section 2

The explanations given with these Science and Technology PYQs for UPSC Prelims are designed to help candidates revise the underlying concepts rather than simply memorize answers.

21. (d) — All three are characteristics of geostationary satellites.
22. (d) — All three associations are valid.
23. (a) — NavIC is India’s regional navigation system; navigation systems provide positioning and timing.
24. (a) — Launch vehicles place payloads into required trajectories/orbits.
25. (a) — Cryogenic engines can use liquid hydrogen/liquid oxygen and require extremely low temperatures.
26. (a) — RTGs convert heat from radioactive decay into electrical energy; they are not conventional fission reactors.
27. (a) — Radioactive decay provides continuous power without reliance on sunlight.
28. (d) — All three statements describe gravitational waves correctly.
29. (d) — Fission, fusion and solar energy are correctly described.
30. (a) — Tokamaks are devices used in fusion research.
31. (a) — The event horizon prevents escape of light; stellar collapse is one formation mechanism.
32. (a) — A light-year measures distance.
33. (a) — Massive stars burn nuclear fuel much faster.
34. (a) — Remote sensing operates without physical contact and uses electromagnetic information.
35. (d) — All three are major applications of space technology.
36. (a) — Earth’s atmosphere absorbs/scatters portions of electromagnetic radiation.
37. (a) — Polar orbits support broad Earth coverage but do not remain stationary over one point.
38. (a) — Chandrayaan missions are lunar missions.
39. (d) — Solar activity can produce space-weather effects.
40. (a) — RTGs convert radioactive-decay heat into electricity. The 2024 UPSC paper directly tested RTGs and spacecraft power systems.

Questions related to satellites, space missions, launch vehicles and astronomy require both conceptual clarity and awareness of recent developments. For a more comprehensive revision of this area, see Space Technology for UPSC Prelims 2027.

Section 3: Artificial Intelligence, Digital Technology & Communication — 20 MCQs

Q.41. With reference to Artificial Intelligence, consider the following statements:

1. Machine learning is a subset of artificial intelligence.
2. Machine learning systems can identify patterns from data.
3. Every AI system necessarily possesses human-like consciousness.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.42. Consider the following statements regarding generative AI:

1. It can generate text, images, audio or other forms of content.
2. Large language models are one type of generative AI system.
3. Generative AI always produces factually correct information.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.43. Which one of the following best describes machine learning?

(a) A process in which computers can learn patterns from data and improve performance on a task
(b) A system in which computers operate without any algorithms
(c) A method of storing data only on paper
(d) A technology restricted exclusively to robotics

Q.44. Consider the following pairs:

Which of the pairs given above are correctly matched?

(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.45. With reference to blockchain technology, consider the following statements:

1. It can maintain a distributed record of transactions.
2. Cryptographic techniques can be used to secure records.
3. Every blockchain must be controlled by a single central authority.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 1 only
(c) 2 and 3 only
(d) 1, 2 and 3

Q.46. PYQ-based: UPSC has tested the concept of the metaverse as an interoperable network of three-dimensional virtual worlds. Which technology is particularly relevant to enabling immersive interaction in such environments?

(a) Extended Reality technologies
(b) Conventional typewriters
(c) Analogue television transmission alone
(d) Mechanical refrigeration

Q.47. Consider the following statements regarding the Internet of Things (IoT):

1. It involves interconnected physical devices.
2. Such devices may contain sensors.
3. IoT necessarily requires every device to have a human operator continuously controlling it.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.48. Which one of the following is most closely associated with edge computing?

(a) Processing data closer to where it is generated
(b) Storing all data permanently on paper
(c) Eliminating all computer networks
(d) Generating electricity from nuclear fusion

Q.49. Consider the following statements regarding 5G technology:

1. It can support high data rates.
2. It can reduce communication latency compared with earlier generations in suitable conditions.
3. It has no potential applications in machine-to-machine communication.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.50. With reference to quantum computing, consider the following statements:

1. A quantum bit can exist in a superposition of states.
2. Quantum computing uses phenomena of quantum mechanics.
3. A qubit is identical in all respects to a classical binary bit.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.51. Which one of the following is a potential application of quantum computing?

(a) Solving certain classes of computational problems using quantum algorithms
(b) Replacing all forms of classical computing immediately
(c) Eliminating the need for electricity
(d) Converting all digital information into analogue signals

Q.52. Consider the following statements regarding encryption:

1. Encryption can protect information from unauthorized access.
2. Public-key cryptography uses a pair of related keys.
3. Encryption guarantees that the recipient will always interpret the information correctly.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.53. With reference to cloud computing, consider the following statements:

1. Computing resources can be provided over a network.
2. Users may access software without maintaining all underlying hardware themselves.
3. Cloud computing means that data necessarily exists in only one physical location.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 1 only
(c) 2 and 3 only
(d) 1, 2 and 3

Q.54. Which one of the following best describes a digital twin?

(a) A digital representation of a physical object, system or process that can be used for monitoring or analysis
(b) A duplicate physical machine
(c) A computer virus that copies itself
(d) A satellite orbiting Earth twice simultaneously

Q.55. Consider the following statements regarding deepfakes:

1. They may use AI techniques to manipulate or generate audiovisual content.
2. They can be used to create realistic but fabricated representations of people.
3. Their creation necessarily requires physical alteration of the person being depicted.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 1 only
(c) 2 and 3 only
(d) 1, 2 and 3

Q.56. Which one of the following is an example of Natural Language Processing?

(a) Automatic analysis and generation of human language
(b) Measurement of earthquake magnitude
(c) Production of nuclear fuel
(d) Satellite orbit correction alone

Q.57. Consider the following statements regarding artificial neural networks:

1. They are inspired in part by the organization of biological neural systems.
2. They can be trained using data.
3. They necessarily reproduce the complete functioning of the human brain.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.58. With reference to Web 3.0, consider the following statements:

1. It is often associated with decentralized technologies.
2. Blockchain-based systems may be used in some Web 3.0 applications.
3. It necessarily means that all websites are controlled by one corporation.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.59. PYQ-based: UPSC has asked questions involving technologies such as blockchain and metaverse. Which of the following pairs is correctly matched?

(a) Blockchain — Distributed ledger technology
(b) Metaverse — Radioactive isotope
(c) Quantum computing — Conventional combustion engine
(d) IoT — Nuclear fission

Q.60. Consider the following statements:

1. Artificial Intelligence can be used for image recognition.
2. AI can be used for language translation.
3. AI systems cannot be used for medical image analysis.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Answers — Section 3

41. (a) — Machine learning is a branch of AI; consciousness is not an inherent requirement.
42. (a) — Generative AI creates content; factual accuracy is not guaranteed.
43. (a) — Machine learning identifies patterns from data.
44. (d) — All three are correctly matched.
45. (a) — Distributed records and cryptography are central concepts; blockchains need not have a single controller.
46. (a) — AR, VR and related XR technologies can support immersive environments.
47. (a) — IoT devices can contain sensors and communicate without continuous human control.
48. (a) — Edge computing shifts processing closer to the data source.
49. (a) — High data rates and lower latency are among 5G’s capabilities; machine communication is an important application area.
50. (a) — Superposition and quantum mechanics distinguish qubits from classical bits.
51. (a) — Quantum algorithms target particular computational problems.
52. (a) — Encryption protects confidentiality; public-key systems use related keys.
53. (a) — Cloud computing provides network-based resources and services; physical data may be distributed.
54. (a) — A digital twin represents a physical system digitally.
55. (a) — Deepfakes can be AI-generated or manipulated audiovisual content.
56. (a) — NLP concerns computational processing of human language.
57. (a) — Neural networks are computational models inspired partly by biological systems and trained with data.
58. (a) — Web 3.0 discussions commonly involve decentralization and blockchain.
59. (a) — Blockchain is distributed-ledger technology.
60. (a) — AI has applications in both image recognition and medical imaging.

The 2022 UPSC paper explicitly tested concepts such as Web 3.0, SaaS and digital platforms, demonstrating the examination’s preference for application-oriented digital-technology questions.

With emerging technologies becoming increasingly relevant to competitive examinations, artificial intelligence and digital technology deserve dedicated preparation. Aspirants can continue their preparation with our detailed guide on Artificial Intelligence and Emerging Technologies for UPSC Prelims.

Section 4: Energy, Materials, Environment & Applied Science — 20 MCQs

Q.61. With reference to green hydrogen, consider the following statements:

1. It can be produced using electrolysis powered by renewable electricity.
2. It can be used in fuel cells.
3. Its production necessarily involves combustion of coal.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.62. Consider the following statements regarding hydrogen fuel-cell vehicles:

1. Hydrogen can be used to generate electricity in a fuel cell.
2. Water can be produced as a major exhaust product at the vehicle level.
3. Such vehicles necessarily burn hydrogen in a conventional internal-combustion engine.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.63. PYQ-based: UPSC has asked about the exhaust emission from hydrogen fuel-cell electric vehicles. Which one of the following is the most appropriate answer?

(a) Water vapour
(b) Sulphur dioxide
(c) Carbon monoxide
(d) Lead particles

Q.64. With reference to lithium-ion batteries, consider the following statements:

1. Lithium ions move between the electrodes during charging and discharging.
2. Graphite is commonly used as an anode material.
3. Lithium-ion batteries can never be used in electric vehicles.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.65. Consider the following elements:

1. Lithium
2. Nickel
3. Cobalt
4. Graphite

Which of the above are commonly associated with electrode materials in lithium-ion batteries?

(a) 1, 2 and 3 only
(b) 2 and 4 only
(c) 1 and 4 only
(d) 1, 2, 3 and 4

Q.66. With reference to solid-state batteries, consider the following statements:

1. They use a solid electrolyte.
2. They are being investigated for potentially improving energy density and safety.
3. They necessarily use no lithium.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.67. Which one of the following is most directly associated with carbon capture and storage?

(a) Capturing carbon dioxide and storing it in a suitable long-term storage site
(b) Increasing atmospheric carbon dioxide concentration
(c) Converting oxygen into nitrogen
(d) Eliminating all carbon from living organisms

Q.68. Consider the following statements regarding carbon capture technologies:

1. Carbon dioxide may be captured from industrial sources.
2. Captured carbon dioxide may be stored underground under suitable conditions.
3. Carbon capture necessarily removes all greenhouse gases from the atmosphere.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.69. Which one of the following is a characteristic application of graphene?

(a) Advanced electronic and material applications
(b) Generation of nuclear fission exclusively
(c) Production of ordinary table salt
(d) Biological reproduction of mammals

Q.70. Consider the following statements regarding nanotechnology:

1. It deals with materials and structures at extremely small scales.
2. Nanomaterials can possess properties different from those of bulk materials.
3. Nanoparticles exist only as products manufactured by humans.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.71. With reference to solar photovoltaic cells, consider the following statements:

1. They convert sunlight directly into electricity.
2. Semiconductor materials play an important role.
3. They require combustion of fossil fuels within each cell to generate electricity.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.72. Consider the following statements regarding supercapacitors:

1. They can store electrical energy.
2. They can generally charge and discharge more rapidly than many conventional batteries.
3. They are completely unrelated to electrochemical phenomena.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.73. With reference to biofuels, consider the following statements:

1. Ethanol can be produced from biomass.
2. Biodiesel can be produced from certain vegetable oils and animal fats.
3. All biofuels are necessarily carbon-neutral over their complete life cycle.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.74. Which one of the following is an example of a second-generation biofuel feedstock?

(a) Agricultural residues
(b) Crude petroleum
(c) Natural uranium
(d) Iron ore

Q.75. Consider the following statements regarding fuel cells:

1. A fuel cell converts chemical energy directly into electrical energy through electrochemical reactions.
2. Hydrogen can be used as a fuel in certain fuel cells.
3. Fuel cells necessarily involve combustion in an open flame.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.76. PYQ-based: A recent UPSC question asked about the materials commonly forming EV battery cathodes. Which combination is most appropriately associated with cathode materials in commonly used lithium-ion chemistries?

(a) Lithium, nickel and cobalt
(b) Graphite, silicon and carbon only
(c) Copper, zinc and aluminium only
(d) Iron, silver and mercury only

Q.77. With reference to hydrogen production, consider the following statements:

1. Electrolysis can split water into hydrogen and oxygen.
2. The environmental characteristics of hydrogen depend partly on how it is produced.
3. All hydrogen produced globally is necessarily green hydrogen.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.78. Which one of the following best describes a semiconductor?

(a) A material whose electrical conductivity lies between that of conductors and insulators and can be controlled under suitable conditions
(b) A material that can never conduct electricity
(c) A material that always conducts electricity perfectly
(d) A radioactive material used only in nuclear reactors

Q.79. Consider the following statements regarding semiconductor chips:

1. They can contain transistors.
2. They are essential components of many digital devices.
3. Semiconductor manufacturing has no strategic significance for modern economies.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.80. Which one of the following best reflects the recent UPSC trend in energy-technology questions?

(a) Linking scientific principles with practical applications such as EVs, hydrogen and batteries
(b) Asking only numerical calculations
(c) Restricting questions exclusively to textbook definitions
(d) Avoiding emerging technologies altogether

Answers — Section 4

61. (a) — Renewable-powered electrolysis can produce green hydrogen; hydrogen can be used in fuel cells.
62. (a) — Fuel cells produce electricity electrochemically; water is a major product.
63. (a) — Hydrogen fuel-cell vehicles generally emit water at the vehicle level. The 2024 UPSC paper tested precisely this concept.
64. (a) — Lithium-ion batteries involve ion movement, and graphite is commonly an anode material.
65. (d) — All four are associated with electrode materials in different lithium-ion battery chemistries.
66. (a) — Solid-state batteries use solid electrolytes; lithium remains relevant in many designs.
67. (a) — CCS involves capture and long-term storage of CO₂.
68. (a) — Capture and underground storage are possible; CCS does not remove all greenhouse gases.
69. (a) — Graphene has major electronic, structural and material applications.
70. (a) — Nanomaterials can occur naturally and can have unique properties.
71. (a) — Photovoltaic cells use semiconductors to convert light into electricity.
72. (a) — Supercapacitors store energy and can have rapid charge/discharge characteristics.
73. (a) — Ethanol and biodiesel can be biofuels; life-cycle emissions vary.
74. (a) — Agricultural residues are typical lignocellulosic feedstocks for second-generation biofuels.
75. (a) — Fuel cells use electrochemical reactions rather than conventional combustion.
76. (a) — Lithium, nickel and cobalt are associated with several common cathode chemistries.
77. (a) — Electrolysis produces hydrogen; production method determines its environmental classification.
78. (a) — Semiconductors have controllable conductivity between conventional conductors and insulators.
79. (a) — Transistors and digital electronics depend heavily on semiconductors.
80. (a) — Recent questions increasingly integrate basic science with real-world technologies. The 2025 paper’s EV, UAV and battery questions illustrate this pattern.

Section 5: Mixed Science & Technology — 20 MCQs

Q.81. Consider the following statements regarding drones:

1. Fixed-wing UAVs generally cannot hover like multirotor UAVs.
2. All UAVs necessarily use batteries as their only source of power.
3. Some UAVs can be designed for vertical take-off and landing.

Which of the statements given above are correct?

(a) 1 and 3 only
(b) 1 only
(c) 2 and 3 only
(d) 1, 2 and 3

Q.82. PYQ-based: UPSC 2025 tested whether all UAVs can vertically land, hover automatically and use only batteries. What is the correct conclusion?

(a) All three statements are correct
(b) Only one statement is correct
(c) Only two statements are correct
(d) None of the statements is correct

Q.83. Consider the following statements regarding radar:

1. Radar can be used for monitoring precipitation.
2. Radar can assist in tracking certain moving objects or animals.
3. Radar is based exclusively on visible light.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.84. Which one of the following is the most appropriate application of aerial metagenomics?

(a) Collecting genetic material from environmental air samples to study organisms present in a habitat
(b) Measuring only the altitude of aircraft
(c) Detecting underground petroleum deposits using seismic waves
(d) Producing synthetic metals in space

Q.85. PYQ-based: UPSC 2023 tested the meaning of “aerial metagenomics.” Which option most closely represents the concept?

(a) Collection of DNA from air in a habitat
(b) Genetic study of only birds
(c) Blood collection from animals using aircraft
(d) Drone-based soil excavation

Q.86. Consider the following statements regarding hydrogels:

1. They can absorb substantial amounts of water.
2. They have applications in controlled drug delivery.
3. They are useful only as fuels.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.87. With reference to 3D printing, consider the following statements:

1. It can be used to manufacture certain customized components.
2. It has applications in medical technology.
3. It necessarily uses only metallic materials.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.88. Consider the following statements regarding augmented reality (AR) and virtual reality (VR):

1. AR can overlay digital information onto the user’s view of the physical world.
2. VR can create an immersive computer-generated environment.
3. AR and VR are identical technologies.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.89. Which one of the following is most closely associated with a biosensor?

(a) Detection of a biological or biochemical substance using a sensing element
(b) Measurement of planetary orbits only
(c) Generation of electricity by nuclear fission only
(d) Manufacture of conventional cement only

Q.90. Consider the following statements regarding genetically modified mustard:

1. Genetic engineering can be used to alter reproductive characteristics of plants.
2. Genetic modification is necessarily equivalent to conventional selective breeding.
3. GM crops may be developed with specific traits using introduced genetic material.

Which of the statements given above are correct?

(a) 1 and 3 only
(b) 1 only
(c) 2 and 3 only
(d) 1, 2 and 3

Q.91. Consider the following pairs:

Which of the pairs given above are correctly matched?

(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.92. With reference to LiDAR, consider the following statements:

1. It uses laser light for measuring distance.
2. It can be used for terrain mapping.
3. It necessarily requires visible sunlight to operate.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.93. Consider the following statements regarding optical fibres:

1. They transmit information using light.
2. Total internal reflection is important in conventional optical-fibre transmission.
3. They are generally more susceptible to electromagnetic interference than copper wires.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.94. Which one of the following best explains why nanomaterials can exhibit properties different from bulk materials?

(a) Their large surface-area-to-volume ratio and quantum effects can become significant at small scales.
(b) They contain no atoms.
(c) They are always radioactive.
(d) They cannot interact with light.

Q.95. Consider the following statements regarding vaccines:

1. Vaccines can stimulate the immune system to develop protection against a pathogen or its components.
2. Some vaccines use weakened or inactivated forms of pathogens or components derived from them.
3. Every vaccine must contain a live pathogen capable of causing the disease.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.96. Consider the following statements regarding antibiotics:

1. They are primarily used against bacterial infections.
2. Their unnecessary use can contribute to antimicrobial resistance.
3. They are universally effective against viruses.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.97. Which one of the following is most directly associated with the concept of a smart grid?

(a) Integration of digital monitoring and control with electricity generation, transmission and distribution
(b) Complete elimination of electricity storage
(c) Replacement of all power plants with satellites
(d) Use of electricity only in rural areas

Q.98. Consider the following statements regarding carbon nanotubes:

1. They are nanostructures composed of carbon.
2. They can possess high mechanical strength relative to their weight.
3. They have no possible applications in electronics or materials science.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Q.99. PYQ-based: Recent UPSC Science and Technology questions have repeatedly combined current technologies with basic scientific principles. Which of the following represents this approach most appropriately?

(a) Asking how a technology works and where it is applied
(b) Asking only the year in which an invention was patented
(c) Asking only the name of the scientist associated with a discovery
(d) Asking only numerical constants from physics

Q.100. Consider the following statements about the recent UPSC Science and Technology trend:

1. Questions can combine current affairs with fundamental scientific concepts.
2. Statement-based questions are commonly used.
3. Candidates can rely entirely on memorization without understanding applications.

Which of the statements given above are correct?

(a) 1 and 2 only
(b) 2 only
(c) 1 and 3 only
(d) 1, 2 and 3

Answers — Section 5

81. (a) — Fixed-wing UAVs generally cannot hover; some UAVs are VTOL.
82. (d) — UPSC 2025’s UAV question used all three as over-generalized statements; none was correct.
83. (a) — Radar can monitor precipitation and moving objects; it is not based exclusively on visible light.
84. (a) — Aerial metagenomics involves collecting environmental DNA from air.
85. (a) — This was the concept tested by UPSC in 2023.
86. (a) — Hydrogels absorb water and have biomedical applications including drug delivery.
87. (a) — 3D printing has manufacturing and medical applications and can use many materials.
88. (a) — AR augments the physical world; VR provides a computer-generated immersive environment.
89. (a) — Biosensors detect biological/biochemical targets.
90. (a) — Genetic engineering can alter plant traits, including reproductive characteristics.
91. (d) — All three pairs are correctly matched.
92. (a) — LiDAR uses laser pulses and can map terrain; it does not require sunlight.
93. (a) — Optical fibres transmit light and use total internal reflection; they are resistant to electromagnetic interference.
94. (a) — Nanoscale effects can significantly alter material properties.
95. (a) — Vaccines can use multiple platforms and need not contain a live pathogen.
96. (a) — Antibiotics target bacteria; unnecessary use contributes to resistance.
97. (a) — Smart grids integrate digital sensing, communication and control into electricity systems.
98. (a) — Carbon nanotubes are carbon nanostructures with important material and electronic applications.
99. (a) — This is characteristic of the modern UPSC approach.
100. (a) — Recent papers show integration of concepts, applications and current developments.

What the Last Five Years of UPSC PYQs Tell Us

A study of the 2021–2025 papers shows a clear pattern: UPSC does not treat Science and Technology as a purely factual subject. Instead, questions frequently combine a current technology or scientific term with an underlying concept, application or limitation.

1. Biotechnology remains important

The 2021 paper included questions involving ACE2, DNA/biotechnology-related concepts and chemical substances, while subsequent papers continued to test biotechnology through genetics, GM crops, microorganisms and biological applications.

2. Digital technology has become a regular area

The 2022 paper tested Web 3.0, SaaS and open-source digital platforms, while the 2024 paper included metaverse and emerging digital technologies.

3. Space questions test applications

UPSC has repeatedly used spacecraft, satellites, navigation systems, astronomical concepts and space technologies to test whether candidates understand what a technology does and why it is useful.

4. Energy technology is increasingly application-oriented

The 2024 paper included hydrogen fuel-cell vehicles, while the 2025 paper included alternative powertrain vehicles and EV-battery materials.

5. Emerging technology is not necessarily asked as a direct definition

A candidate may encounter a question about a technology in the form of:

• statements,
• correctly matched pairs,
• application-based questions,
• “how many of the above” questions,
• Statement-I/Statement-II,
• or a technology’s real-world use.

This is why simply memorizing definitions is insufficient.

Five-Year PYQ Topic Map: 2021–2025

The official UPSC archive confirms the availability of the General Studies Paper-I papers for these examination years, while independent topic-wise compilations identify Science & Technology questions across these papers.

How to Use Science and Technology PYQs for UPSC Prelims

Regular revision of Science and Technology PYQs for UPSC Prelims should be combined with current affairs and basic conceptual study.

Do not simply memorize the answer to each PYQ.

For every question, ask:

1. What concept is being tested?

For example:

UAV → VTOL → hovering → propulsion

2. Why is the statement correct or incorrect?

This helps with UPSC’s statement-based questions.

3. What related concepts can UPSC ask next?

For example:

Green Hydrogen

→ Electrolysis
→ Renewable electricity
→ Fuel cells
→ Hydrogen blending
→ Storage
→ Transport
→ National Green Hydrogen Mission

4. Can you eliminate options?

UPSC frequently creates one or more statements that are too absolute.

Words such as:

• always
• only
• all
• necessarily
• completely
• never

deserve particular attention.

5. Connect current affairs with static science

A current event involving an EV battery should lead you to revise:

Lithium → Cathode → Anode → Electrolyte → Energy density → Charging → Battery chemistry

This approach is more useful than memorizing the current-affairs headline alone.

After completing these Science and Technology PYQs for UPSC Prelims, candidates should revise the concepts behind the questions and then practise topic-wise current-affairs questions. Our Science And Technology 100 MCQs for UPSC 2027 with Answers provide an additional way to test this preparation.

How to Prepare with Science and Technology PYQs for UPSC Prelims: Final Revision Strategy

For Science and Technology PYQs for UPSC Prelims, divide your preparation into these major clusters:

Biotechnology
→ DNA → RNA → CRISPR → GMOs → Stem Cells → Vaccines → Gene Therapy

Space Technology
→ Satellites → Orbits → Launch Vehicles → Navigation → Space Missions → Astronomy

Digital Technology
→ AI → Machine Learning → Generative AI → Blockchain → Web 3.0 → IoT → Cloud → Quantum Computing

Energy Technology
→ Hydrogen → Fuel Cells → EVs → Batteries → Nuclear Energy → Fusion → Solar

Materials Science
→ Nanotechnology → Graphene → Nanoparticles → Semiconductors → Advanced Materials

Health Technology
→ Vaccines → Diagnostics → Gene Therapy → Antimicrobial Resistance → Medical Imaging

Defence Technology
→ UAVs → Missiles → Radar → Electronic Warfare → Hypersonic Technology

The strongest preparation strategy is therefore concept + application + current affairs + PYQ rather than isolated fact memorization.

While solving Science and Technology PYQs for UPSC Prelims, focus on why each option is correct or incorrect rather than memorising only the final answer.

Most Important Resources for UPSC Prelims 2027

• Current Affairs For UPSC Prelims 2027
• Polity for UPSC Prelims 2027
• Economy for UPSC Prelims 2027
• History for UPSC Prelims 2027
• Science and Technology for UPSC Prelims 2027
• Geography for UPSC Prelims 2027

Conclusion

Science and Technology PYQs for UPSC Prelims are valuable because they reveal how UPSC converts scientific developments into analytical multiple-choice questions. The 2021–2025 papers show that the examination repeatedly connects basic scientific principles with emerging technologies, real-world applications and contemporary developments.

Aspirants should therefore use previous-year questions not merely as a test of memory but as a roadmap for identifying concepts, understanding applications and predicting the areas that require deeper revision.

Consistent practice of Science and Technology PYQs for UPSC Prelims, along with current affairs and conceptual revision, can help aspirants become familiar with the analytical nature of Science and Technology questions.

For authentic preparation, candidates should always cross-check question wording and official papers against the UPSC’s own Previous Question Papers repository, rather than relying exclusively on coaching compilations.

This 100-question practice set is designed to complement the actual UPSC PYQs, not replace them.

External Resources

ISRO Space Science and Exploration

ISRO Spacecraft Missions

For serious preparation, aspirants should combine conceptual understanding with previous-year questions and authentic government sources. UPSC Previous Year Question Papers can help candidates understand the actual framing and difficulty of Civil Services Preliminary questions.

Before moving to advanced Science and Technology topics, candidates should strengthen their basic scientific concepts through school-level textbooks. The NCERT Textbooks portal provides access to official textbooks from Classes I–XII and can be useful for revising fundamental concepts.