UPSC solved previous year questions

UPSC Science and technology PYQ with Answers

144 solved Science and technology questions from previous UPSC papers, each with an answer and explanation.

Questions
144
Years covered
2016–2026
Exam years
11
With answers
144

Science and technology questions by year

UPSC Science and technology PYQ with Answers

21–31 of 31
  1. Q23 2024 Prelims GS

    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 spacecraft.
    3. RTGs can use Plutonium-238, which is a by-product of weapons development.
    Which of the statements given above are correct?

    1. 1 and 2 only
    2. 2 and 3 onlyβœ“
    3. 1 and 3 only
    4. 1, 2 and 3
    Answer explanation

    2 and 3 only Statement 1 is incorrect because RTGs are not fission reactors. They convert heat released by radioactive decay directly into electricity through thermoelectric materials; they do not sustain a nuclear fission chain reaction.…

    Radioisotope power systemsRadioisotope thermoelectric generatorsScience and technology
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  2. Q24 2024 Prelims GS

    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?

    1. Both Statement-I and Statement-II are correct and Statement-II explains Statement-I.
    2. Both Statement-I and Statement-II are correct, but Statement-II does not explain Statement-I.
    3. Statement-I is correct, but Statement-II is incorrect.
    4. Statement-I is incorrect, but Statement-II is correct.βœ“
    Answer explanation

    Statement-I is incorrect, but Statement-II is correct. Statement-I is incorrect because massive, luminous giant stars generally consume their nuclear fuel much faster and therefore have shorter lifetimes than low-mass dwarf stars such as…

    AstronomyScience and technologyStellar evolution
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  3. Q25 2024 Prelims GS

    Which one of the following is synthesised in the human body that dilates blood vessels and increases blood flow?

    1. Nitric oxideβœ“
    2. Nitrous oxide
    3. Nitrogen dioxide
    4. Nitrogen pentoxide
    Answer explanation

    Nitric oxide Nitric oxide (NO) is synthesized by endothelial cells and acts as a signalling molecule that relaxes vascular smooth muscle, causing vasodilation and increasing blood flow.…

    Cellular signallingHuman physiologyNitric oxide and vasodilation
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  4. Q26 2024 Prelims GS

    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?

    1. Only one
    2. Only two
    3. All threeβœ“
    4. None
    Answer explanation

    All three Radar and related electromagnetic sensing technologies have applications across all three activities. Advanced radar-based or millimetre-wave screening systems can assist in security screening, including the detection of…

    Radar applicationsRemote sensingScience and technology
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  5. Q27 2024 Prelims GS

    Consider the following aircraft:
    1. Rafale
    2. MiG-29
    3. Tejas MK-1
    How many of the above are considered fifth-generation fighter aircraft?

    1. Only one
    2. Only two
    3. All three
    4. Noneβœ“
    Answer explanation

    None The Rafale is generally classified as a 4.5-generation multirole fighter. The MiG-29 is a fourth-generation fighter, while the Tejas Mk-1 is also generally classified as a fourth-generation light combat aircraft.…

    Fighter aircraft generationsMig-29 and tejas classificationMilitary aviation
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  6. Q28 2024 Prelims GS

    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:

    1. 1 only
    2. 1 and 2 only
    3. 2 and 3 only
    4. 1, 2 and 3βœ“
    Answer explanation

    1, 2 and 3 Statement 1 is correct because hydrogels can absorb and retain water and are used in controlled drug-delivery systems.…

    Biomedical and industrial applicationsHydrogelsMaterials science
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  7. Q30 2024 Prelims GS

    Recently, the term β€œpumped-storage hydropower” is actually and appropriately discussed in the context of which one of the following?

    1. Irrigation of terraced crop fields
    2. Lift irrigation of cereal crops
    3. Long duration energy storageβœ“
    4. Rainwater harvesting system
    Answer explanation

    Long duration energy storage Pumped-storage hydropower stores energy by pumping water from a lower reservoir to a higher reservoir when electricity is available or demand is low.…

    Energy storageGrid-scale electricity balancingPumped-storage hydropower
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  8. Q31 2024 Prelims GS

    Which one of the following words/phrases is most appropriately used to denote β€œan interoperable network of 3D virtual worlds that can be accessed simultaneously by millions of users, who can exert property rights over virtual items”?

    1. Big data analytics
    2. Cryptography
    3. Metaverseβœ“
    4. Virtual matrix
    Answer explanation

    Metaverse The metaverse refers to interconnected, persistent 3D virtual environments in which many users can interact, often through digital avatars and with ownership or control over virtual items.…

    Digital technologiesMetaverseScience and technology
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