UPSC Prelims Science & Technology previous year questions from 2024, with answers and explanations.
2024Multi-statement (How Many Style)Clean Energy & Materials
Consider the following:
1. Battery storage
2. Biomass generators
3. Fuel cells
4. Rooftop solar photovoltaic units
How many of the above are considered "Distributed Energy Resources"?
A.Only one
B.Only two
C.Only three
D.All four
Explanation: * Items 1, 2, 3, and 4 are correct: Distributed Energy Resources (DERs) include any small-scale, decentralized technologies or devices that can produce, store, or manage electricity situated close to the consumer's end of the meter. * This classification covers rooftop solar photovoltaic arrays, localized small wind turbines, biomass generators, fuel cells, and micro-scale battery storage units. Thus, all four are DERs.
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2024Multi-statement (Traditional Style)Space Technology & Astronomy
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
Explanation: * Statement 1 is incorrect: RTGs are not fission reactors; they do not split atoms via a chain reaction. Instead, they are compact power units that convert heat generated by the natural radioactive decay of unstable isotopes directly into electricity. * Statement 2 is correct: Due to their high reliability, lack of moving components, and independence from solar proximity, RTGs are extensively utilized to power the onboard electronic electronics of deep-space probes and spacecraft. * Statement 3 is correct: These generators commonly rely on Plutonium-238 as an isotopic fuel source. Plutonium-238 has a favorable half-life and is generated as a specialized material by-product during weapons-grade plutonium processing activities.
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2024Statement-I & Statement-II (Assertion-Reason Style)Space Technology & Astronomy
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
Explanation: * Statement-I is incorrect: High-mass giant stars hold much hotter and denser internal cores than smaller dwarf stars. This intense internal pressure causes giant stars to burn through their foundational core hydrogen fuel supply at a drastically faster rate, causing them to have significantly shorter lifespans than dwarf stars. * Statement-II is correct: Because of their immense mass, density, and core temperature parameters, giant stars experience a much higher rate of fusion and nuclear reactions than dwarf stars. Thus, option (d) is correct.
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2024Direct Conceptual / Factual MCQBiotechnology & Healthcare
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
Explanation: * (a) Nitric oxide is correct: Nitric oxide (NO) is an essential cell-signaling molecule naturally synthesized within the endothelial lining of human blood vessels. It acts as a powerful vasodilator that relaxes vascular smooth muscle tissue, causing blood vessels to widen, which increases blood flow and safely modulates blood pressure.
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2024Multi-statement (How Many Style)Defense & Aerospace
Consider the following activities:
1. Tracking the migration of animals
2. Identification of narcotics on passengers at airports or in aircraft
3. Monitoring of precipitation
In how many of the above activities can the radars be used?
A.Only one
B.Only two
C.All three
D.None of the above statements is correct
Explanation: * Activity 1 is incorrect: Conventional airport security checkpoints utilize X-ray transmission systems, millimeter-wave scanners, or chemical trace detectors to uncover narcotics and hidden materials on passengers, rather than standard long-wave radar trackers. * Activity 2 is correct: Specialized Doppler weather radars are widely deployed by meteorological departments to monitor precipitation density, map storms, and track rainfall patterns. * Activity 3 is correct: Radar systems are valuable tools used by wildlife researchers to map, track, and examine the migration speeds, flight altitudes, and velocities of flocks of birds or animals across distances. * Therefore, radars are used in exactly two activities.
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2024Multi-statement (Traditional Style)Clean Energy & Materials
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
Explanation: * Application 1 is correct: Because hydrogels consist of highly cross-linked, biocompatible hydrophilic polymer networks that swell in fluids, they serve as excellent vehicles to enable time-controlled localized drug delivery in patients. * Application 2 is correct: Their high water-retention and evaporative characteristics are increasingly leveraged to build passive cooling loops and custom components for air-conditioning and electronics systems. * Application 3 is correct: Advanced research indicates that hydrogels can operate as highly efficient industrial bio-lubricants due to their excellent anti-friction and wear-resistant properties.
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2024Direct Conceptual / Factual MCQClean Energy & Materials
Which one of the following is the exhaust pipe emission from Fuel Cell Electric Vehicles, powered by hydrogen?
A.Hydrogen peroxide
B.Hydronium
C.Oxygen
D.Water vapour
Explanation: * (d) Water vapour is correct: Fuel Cell Electric Vehicles (FCEVs) use onboard fuel cells to combine compressed hydrogen gas with atmospheric oxygen, generating electricity to drive an electric motor. This clean electrochemical process generates no toxic tailpipe pollution, releasing only pure water vapor and warm air as byproducts.
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2024Direct Conceptual / Factual MCQClean Energy & Materials
Recently, the term "pumped-storage hydropower" is actually and appropriately discussed in the context of which one of the following?
A.Field irrigation
B.Lift irrigation
C.Long duration energy storage
D.Rainwater harvesting
Explanation: * (c) Long duration energy storage is correct: Pumped-Storage Hydropower (PSH) is a configuration of two water reservoirs placed at different elevations. During periods of low power demand, cheap excess grid electricity is used to pump water up to the higher reservoir. When demand peaks, the water is released downward to spin turbines and generate power, acting as a massive, highly efficient long-duration utility energy storage system.
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2024Direct Conceptual / Factual MCQIT, AI & Electronics
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
Explanation: * (c) Metaverse is correct: The term metaverse refers to a shared, immersive, and highly persistent network of 3D virtual spaces where multiple users interact via avatars. Powered by augmented reality, virtual reality, and blockchain networks, it allows user interaction, social/economic connections, and the assertion of property rights over distinct digital assets.
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