UPSC Prelims · Science & Technology PYQ
Solar and renewable energy, nuclear reactors and safeguards, fuel cells, and alternative-powertrain vehicles — a fast-growing current-affairs-linked Science & Technology topic.
Includes
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?
Correct answer: C. All the three
Explanation
Full battery electric vehicles, hydrogen fuel cell vehicles, and fuel cell-electric hybrids all move away from conventional internal combustion engines, making all three legitimate examples of alternative powertrain technology.
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"?
Correct answer: D. All four
Explanation
Battery storage, biomass generators, fuel cells, and rooftop solar photovoltaic units are all examples of small-scale, decentralised power sources located close to where electricity is consumed, making all four Distributed Energy Resources.
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?
Correct answer: B. 2 and 3 only
Explanation
RTGs actually generate electricity from the natural radioactive decay of isotopes, not from a fission chain reaction, making statement 1 false; they are indeed used to power onboard spacecraft systems (statement 2 true) and commonly use Plutonium-238, historically a by-product of nuclear weapons material production (statement 3 true).
Consider the following materials: 1. Agricultural residues 2. Corn grain 3. Wastewater treatment sludge 4. Wood mill waste Which of the above can be used as feedstock for producing Sustainable Aviation Fuel?
Correct answer: C. 1, 2, 3 and 4
Explanation
A wide range of biomass sources, including agricultural residues, corn grain, wastewater treatment sludge, and wood mill waste, can all serve as feedstock for producing Sustainable Aviation Fuel through various conversion pathways.
With reference to the role of biofilters in Recirculating Aquaculture System, consider the following statements : 1. Biofilters provide waste treatment by removing uneaten fish feed. 2. Biofilters convert ammonia present in fish waste to nitrate. 3. Biofilters increase phosphorus as nutrient for fish in water. How many of the statements given above are correct?
Correct answer: B. Only two
Explanation
Biofilters do remove waste like uneaten feed and convert toxic ammonia from fish waste into less harmful nitrate through nitrifying bacteria (statements 1 and 2 true), but they do not add phosphorus to the water for fish nutrition, making statement 3 false.
With reference to green hydrogen, consider the following statements : 1. It can be used directly as a fuel for internal combustion. 2. It can be blended with natural gas and used as fuel for heat or power generation. 3. It can be used in the hydrogen fuel cell to run vehicles. How many of the above statements are correct?
Correct answer: C. All three
Explanation
Green hydrogen can indeed be burned directly as a fuel, blended with natural gas for heat or power generation, and used in fuel cells to run vehicles, making all three uses valid.
With reference to street-lighting, how do sodium lamps differ from LED lamps? 1. Sodium lamps produce light in 360 degrees but it is not so in the case of LED lamps. 2. As street-lights, sodium lamps have longer life span than LED lamps. 3. The spectrum of visible light from sodium lamps is almost monochromatic while LED lamps offer significant colour advantages in street-lighting. Select the correct answer using the code given below.
Correct answer: C. 1 and 3 only
Explanation
Sodium lamps do emit light in essentially all directions while LED lamps are more directional (statement 1 true), and sodium lamps produce a nearly monochromatic yellow-orange light compared to the fuller colour spectrum LEDs can offer (statement 3 true); however LED lamps generally have a longer operational lifespan than sodium lamps, making statement 2 false.
In India, why are some nuclear reactors kept under “IAEA Safeguards” while others are not?
Correct answer: B. Some use imported uranium and others use domestic supplies
Explanation
India's nuclear reactors using imported uranium fall under IAEA Safeguards as a condition of that supply agreement, while reactors relying on domestically sourced uranium are not bound by the same external inspection requirement.
With reference to solar water pumps, consider the following statements: 1. Solar power can be used for running surface pumps but not for submersible pumps. 2. Solar power can be used for running centrifugal pumps but not the ones with piston. Which of the statements given above is/are correct?
Correct answer: D. Neither 1 nor 2
Explanation
Solar power can actually run both surface and submersible pumps, and it can power both centrifugal and piston-type pumps depending on the system design, making both restrictive statements about solar pump limitations false.
In the context of proposals to the use of hydrogen-enriched CNG (H-CNG) as fuel for buses in public transport, consider the following statements: 1. The main advantage of the use of H-CNG is the elimination of carbon monoxide emissions. 2. H-CNG as fuel reduces carbon dioxide and hydrocarbon emissions. 3. Hydrogen up to one-fifth by volume can be blended with CNG as fuel for buses. 4. H-CNG makes the fuel less expensive than CNG. Which of the statements given above is/are correct?
Correct answer: B. 2 and 3 only
Explanation
H-CNG use does reduce carbon dioxide and hydrocarbon emissions compared to plain CNG (statement 2 true), and up to about 18% (close to one-fifth) hydrogen by volume can be blended into CNG for use as bus fuel (statement 3 true); however it does not eliminate carbon monoxide emissions entirely, and it does not make the fuel cheaper than CNG, making statements 1 and 4 false.
What is/are the consequence/consequences of a country becoming the member of the 'Nuclear Suppliers Group'? 1. It will have access to the latest and most efficient nuclear technologies. 2. It automatically becomes a member of 'The Treaty on the Non-Proliferation of Nuclear Weapons (NPT)'. Which of the statements given above is/are correct?
Correct answer: A. 1 only
Explanation
Nuclear Suppliers Group membership does grant access to advanced nuclear technology and trade among member states (statement 1 true), but it is a separate, distinct arrangement from the NPT, and joining the NSG does not automatically confer NPT membership, making statement 2 false.
In the Indian context, what is the implication of ratifying the ‘Additional Protocol’ with the ‘International Atomic Energy Agency (IAEAY ?
Correct answer: A. The civilian nuclear reactors come under IAFA safeguards.
Explanation
Signing the Additional Protocol with the IAEA brings a country's civilian nuclear facilities under IAEA safeguards and monitoring, allowing greater international verification of peaceful nuclear use.
With reference to solar power production in India, consider the following statements: 1. India is the third largest in the world in the manufacture of silicon wafers used in photovoltaic units. 2. The solar power tariffs are determined by the Solar Energy Corporation of India. Which of the statements given above is/are correct?
Correct answer: D. Neither 1 nor 2
Explanation
India was not, at the time, ranked third globally in silicon wafer manufacturing for photovoltaics, and solar power tariffs in India are typically determined through competitive bidding or state electricity regulatory commissions rather than solely by the Solar Energy Corporation of India, making both statements false.
It is possible to produce algae-based biofuels, but what is/are the likely limitation(s) of developing countries in promoting this industry? 1. Production of algae-based biofuels is possible in seas only and not on continents. 2. Setting up and engineering the algae-based biofuel production requires high level of expertise/technology until the construction is completed. 3. Economically viable production necessitates the setting up of large-scale facilities which may raise ecological and social concerns. Select the correct answer using the code given below:
Correct answer: B. 2 and 3 only
Explanation
Setting up algae-based biofuel production does demand a high level of technical expertise during construction (statement 2 true), and achieving economic viability typically requires large-scale facilities that can raise genuine ecological and social concerns (statement 3 true); however algae-based biofuel production is not restricted to seas only, since it can also be done using freshwater or land-based systems, making statement 1 false.
Consider the following statements: 1. The Nuclear Security Summits are periodically held under the aegis of the United Nations. 2. The International Panel on Fissile Materials is an organ of International Atomic Energy Agency. Which of the statements given above is/are correct?
Correct answer: D. Neither 1 nor 2
Explanation
Nuclear Security Summits were held under a dedicated multinational diplomatic initiative rather than under direct United Nations auspices, making statement 1 false; and the International Panel on Fissile Materials is an independent research group, not a formal organ of the IAEA, making statement 2 also inaccurate.
India is an important member of the ‘International Thermonuclear Experimental Reactor’. If this experiment succeeds, what is the immediate advantage for India?
Correct answer: D. It can build fusion reactors for power generation.
Explanation
The International Thermonuclear Experimental Reactor (ITER) project aims to demonstrate the feasibility of nuclear fusion, so its success would directly advance India's ability to build fusion-based power reactors.
With reference to 'fuel cells' in which hydrogen-rich fuel and oxygen are used to generate electricity, consider the following statements: 1. If pure hydrogen is used as a fuel, the fuel cell emits heat and water as by-products. 2. Fuel cells can be used for powering buildings and not for small devices like laptop computers. 3. Fuel cells produce electricity in the form of Alternating Current (AC). Which of the statements given above is/are correct?
Correct answer: A. 1 only
Explanation
A hydrogen fuel cell running on pure hydrogen produces only heat and water as by-products, with no harmful emissions, making statement 1 correct; however fuel cells are versatile and can power devices ranging from small electronics to buildings (making statement 2 false), and they generate electricity as Direct Current, not Alternating Current, making statement 3 false as well.
With reference to technologies for solar power production, consider the following statements: 1. 'Photovoltaics' is a technology that generates electricity by direct conversion of light into electricity, while 'Solar Thermal' is a technology that utilizes the Sun's rays to generate heat which is further used in electricity generation process. 2. Photovoltaics generates Alternating Current (AC), while Solar Thermal generates Direct Current (DC). 3. India has manufacturing base for Solar Thermal technology, but not for Photovoltaics. Which of the statements given above is/are correct?
Correct answer: A. 1 only
Explanation
Photovoltaic technology directly converts sunlight into electricity, while solar thermal technology captures the sun's heat to eventually generate power, correctly describing the fundamental difference between the two approaches (statement 1 true); however solar PV actually generates Direct Current (not AC) and India has manufacturing capability in both photovoltaic and solar thermal technology, making statements 2 and 3 inaccurate.
In India, cluster bean (Guar) is traditionally used as a vegetable or animal feed, but recently the cultivation of this has assumed significance. Which one of the following statements is correct in this context?
Correct answer: B. The gum made from its seeds is used in the extraction of shale gas
Explanation
Guar gum, extracted from cluster bean seeds, has gained industrial importance because of its use as a key additive in the hydraulic fracturing process used to extract shale gas.
What is the role of ultraviolet (UV) radiation in the water purification systems? 1. It inactivates/kills the harmful microorganisms in water. 2. It removes all the undesirable odours from the water. 3. It quickens the sedimentation of solid particles, removes turbidity and improves the clarity of water. Which of the statements given above is/are correct?
Correct answer: A. 1 only
Explanation
UV radiation in water purification effectively inactivates and kills harmful microorganisms (statement 1 true), but it does not remove bad odours or improve water clarity by aiding sediment settling, since UV treatment works purely at the microbial disinfection level and does not alter the water's physical or chemical impurities, making statements 2 and 3 false.
To meet its rapidly growing energy demand, some opine that India should pursue research and development on thorium as the future fuel of nuclear energy. In this context, what advantage does thorium hold over uranium? 1. Thorium is far more abundant in nature than uranium. 2. On the basis of per unit mass of mined mineral, thorium can generate more energy compared to natural uranium. 3. Thorium produces less harmful waste compared to uranium. Which of the statements given above is/are correct?
Correct answer: D. 1, 2 and 3
Explanation
Thorium is significantly more abundant in nature than uranium (statement 1 true), can potentially yield more energy per unit mass of mined mineral in advanced reactor designs (statement 2 true), and produces comparatively less long-lived, harmful radioactive waste than conventional uranium fuel cycles (statement 3 true).
Microbial fuel cells are considered a source of sustainable energy. Why? 1. They use living organisms as catalysts to generate electricity from certain substrates. 2. They use a variety of inorganic materials as substrates. 3. They can be installed in waste water treatment plants to cleanse water and produce electricity. Which of the statements given above is/are correct?
Correct answer: C. 1 and 3 only
Explanation
Microbial fuel cells use living microorganisms as biological catalysts to generate electricity from organic substrates (statement 1 true), and they can indeed be deployed in wastewater treatment plants to simultaneously clean water and produce electricity (statement 3 true); however they primarily use organic (not simply inorganic) substrates as their energy source, making statement 2 false.
The function of heavy water in a nuclear reactor is to
Correct answer: A. Slow down the speed of neutrons
Explanation
Heavy water in a nuclear reactor acts as a moderator, slowing down fast neutrons so they are more likely to sustain the nuclear fission chain reaction efficiently.
What is the difference between a CFL and an LED lamp? 1. To produce light, a CFL uses mercury vapour and phosphor while an LED lamp uses semi-conductor material. 2. The average life span of a CFL is much longer than that of an LED lamp. 3. A CFL is less energy-efficient as compared to an LED lamp. Which of the statements given above is/are correct?
Correct answer: C. 1 and 3 only
Explanation
A CFL uses mercury vapour and a phosphor coating to produce light, while an LED relies on semiconductor material (statement 1 true), and LEDs are indeed considerably more energy-efficient than CFLs (statement 3 true); however CFLs generally have a shorter lifespan than LEDs, not longer, making statement 2 false.
Hydrogen fuel-cell vehicles produce one of the following as “exhaust”.
Correct answer: C. H₂O
Explanation
Hydrogen fuel-cell vehicles combine hydrogen with oxygen to produce electricity, releasing water as their primary exhaust by-product.
In a dry cell (battery), which of the following are used as electrolytes?
Correct answer: A. Ammonium chloride and Zinc chloride
Explanation
A typical dry cell battery uses a moist paste of ammonium chloride and zinc chloride as its electrolyte.
In the year 2007, an earthquake led to massive radioactive water leakage in the largest nuclear plant in the world. In which country did it occur?
Correct answer: C. Japan
Explanation
In 2007, an earthquake caused radioactive water leakage at the Kashiwazaki-Kariwa nuclear power plant, the world's largest, located in Japan.
In which one of the following locations is the International Thermonuclear Experimental Reactor (ITER) project to be built?
Correct answer: B. Southern France
Explanation
The International Thermonuclear Experimental Reactor (ITER) is being built in Cadarache, in southern France.
Where was the first desalination plant in India to produce one lakh litres freshwater per day based on low temperature thermal desalination principle commissioned?
Correct answer: A. Kavaratti
Explanation
India's first low-temperature thermal desalination plant producing about one lakh litres of freshwater daily was commissioned at Kavaratti in the Lakshadweep islands.
With which one of the following is BRIT (Government of India) engaged?
Correct answer: C. Isotope Technology
Explanation
The Board of Radiation and Isotope Technology (BRIT), under India's Department of Atomic Energy, is engaged in the production and application of radioisotope technology.
Recently, the European Union and six other countries including India signed the International Thermonuclear Experimental Reactor (ITER) Project. Which one of the following was NOT a signatory to it?
Correct answer: A. Canada
Explanation
Canada was not among the signatories to the ITER project agreement, unlike China, Japan, and the USA, which were founding partner countries.
In which one of the following areas did the Indira Gandhi Center for Atomic Research make significant progress in the year 2005?
Correct answer: A. Re-processing the uranium-plutonium mixed carbide fuel of the Fast Breeder Test Reactor
Explanation
In 2005, the Indira Gandhi Centre for Atomic Research made notable progress in reprocessing the mixed uranium-plutonium carbide fuel used in the Fast Breeder Test Reactor.
Assertion (A): The main constituent of the Liquefied Petroleum Gas is methane. Reason (R): Methane can be used directly for burning in homes and factories where it can be supplied through pipelines.
Correct answer: D. A is false but R is true
Explanation
The main constituent of LPG is actually a mixture of butane and propane, not methane, making the assertion false; methane, however, is genuinely a fuel that can be piped directly to homes and factories for combustion, making the reason a true statement on its own.
Match List-I (Atomic Power Plants/Heavy Water Plants) with List-II (State) and select the correct answer using the code given below the lists : List-I (A) Thal (B) Manuguru (C) Kakrapar (D) Kaiga List-II (State) 1. Andhra Pradesh 2. Gujarat 3. Maharastra 4. Maha 5. Karnataka
Correct answer: D. 3 1 2 5
Explanation
Matching these Indian atomic power and heavy water facilities to their states: Thal is in Maharashtra, Manuguru is in Andhra Pradesh (Telangana region), Kakrapar is in Gujarat, and Kaiga is in Karnataka, giving the pairing A-3, B-1, C-2, D-5.
Consider the following statements: 1. Indira Gandhi Centre for Atomic Research uses fast reactor technology. 2. Atomic Minerals Directorate for Research and Exploration is engaged in heavy water production. 3. Indian Rare Earths Limited is engaged in the manufacture of Zircon for India's nuclear programme beside other rare earth products. Which of these statements given above are correct?
Correct answer: C. 1 and 3
Explanation
The Indira Gandhi Centre for Atomic Research does specialise in fast reactor technology (statement 1 true), and Indian Rare Earths Limited is indeed engaged in manufacturing zircon and other rare-earth products supporting India's nuclear programme (statement 3 true); however heavy water production is primarily handled by the Heavy Water Board rather than the Atomic Minerals Directorate, which focuses on mineral exploration, making statement 2 false.
Match List I (Fuel Gases) with List II (Major Constituents) and select the correct answer using the codes given below: List I (A) CNG (B) Coal gas (C) LPG (D) Water gas List II 1. Carbon monoxide, Hydrogen 2. Butane, Propane 3. Methane, Ethane 4. Hydrogen, Methane, Carbon monoxide Codes:
Correct answer: B. A 3 B 4 C 2 D 1
Explanation
CNG is predominantly methane, coal gas contains a mixture including hydrogen and carbon monoxide, LPG consists mainly of butane and propane, and water gas is composed of carbon monoxide and hydrogen, matching the pairing A-3, B-4, C-2, D-1.
Consider the following organisations: I. Atomic Minerals Directorate for Research and Exploration II. Heavy Water Board III. Indian Rare Earths Limited IV. Uranium Corporation of India Which of these is/are under the Department of Atomic Energy?
Correct answer: D. I, II, III and IV
Explanation
The Atomic Minerals Directorate for Research and Exploration, Heavy Water Board, Indian Rare Earths Limited, and Uranium Corporation of India are all constituent units functioning under India's Department of Atomic Energy.
Consider the following statements: In a nuclear reactor, self-sustained chain reaction is possible, because I. More neutrons are released in each of the fission reactions. II. The neutrons immediately take part in the fission process. III. The fast neutrons are slowed down by Graphite. IV. Every neutron released in the fission reaction initiates further fission. Which of these statements are correct?
Correct answer: B. I and III
Explanation
A self-sustained nuclear chain reaction occurs because each fission event releases multiple neutrons, and these released neutrons must go on to trigger further fission events, matching statements I and III as the fundamental physical basis, since it is the multiplication and continuation of fission-inducing neutrons (aided by a moderator to slow them) that sustains the reaction.
A radioactive substance has a half-life of four months. Three fourth of the substance would decay in
Correct answer: C. 8 months
Explanation
With a four-month half-life, half the substance decays in the first four months, leaving a quarter remaining after the second four-month period, meaning three-quarters has decayed by the end of two half-lives, or eight months.
Consider the following features of newer models of motor cars: I. Radial tyres II. Streamlined body III. Multipoint fuel injection IV. Catalytic converter with exhaust Which of these features make the newer models of motor cars more fuel-efficient?
Correct answer: B. II and III
Explanation
A streamlined body reduces air resistance and multipoint fuel injection improves combustion efficiency, both directly enhancing a car's fuel economy, unlike radial tyres or catalytic converters, which primarily affect grip/durability and emissions control respectively rather than fuel efficiency itself.
Consider the following statements regarding a motor car battery: I. The voltage is usually 12 V. II. Electrolyte used is hydrochloric acid. III. Electrodes are lead and copper. IV. Capacity is expressed in ampere-hour. Which of the above statements are correct?
Correct answer: D. I and IV
Explanation
A standard motor car battery typically operates at 12 volts (statement I true) and its storage capacity is measured in ampere-hours (statement IV true); however its electrolyte is dilute sulfuric acid, not hydrochloric acid, and its electrodes are lead and lead dioxide, not lead and copper, making statements II and III false.
Which one of the following elements is essential for the construction of nuclear reactors?
Correct answer: C. Zirconium
Explanation
Zirconium, valued for its low neutron-absorption and corrosion resistance, is a key structural material used in the construction of nuclear reactor cores and fuel cladding.
Which one of the following has the highest fuel value?
Correct answer: A. Hydrogen
Explanation
Hydrogen has the highest fuel value (energy released per unit mass) among the listed options, significantly exceeding that of natural gas, charcoal, or gasoline.
Consider the following statements: At the present level of technology available in India, solar energy can be conveniently used to I. Supply hot water to residential buildings. II. Supply water for minor irrigation projects. III. Provide street lighting. IV. Electrify a cluster of villages and small towns. Of these statements
Correct answer: D. I, II and III are correct
Explanation
At India's technology level at the time, solar energy could be practically used to heat water for buildings, power street lighting, and electrify small village and town clusters, but supplying enough energy for minor irrigation projects at scale was not yet considered a convenient application, making statements I, III, and IV the correct combination.
Which one of the following pairs of materials serves as electrodes in chargeable batteries commonly used in devices such as torchlights, electric shavers, etc.?
Correct answer: A. Nickel and cadmium
Explanation
Rechargeable batteries commonly used in devices like torchlights and electric shavers typically use nickel and cadmium as their electrode materials.
The difference between a nuclear reactor and an atomic bomb is that
Correct answer: B. the chain reaction in nuclear reactor is controlled
Explanation
The essential difference between a nuclear reactor and an atomic bomb is that in a reactor the nuclear chain reaction is carefully controlled and moderated to release energy steadily, while in a bomb it proceeds uncontrolled almost instantaneously.
‘Yellow cake’, an item of smuggling across borders is
Correct answer: C. uranium oxide
Explanation
'Yellow cake' refers to a partially refined form of uranium oxide, a key intermediate product in the nuclear fuel production process.