1. (a) Only one
2. (b) Only two
3. (c) All the three
4. (d) None

Answer: (c) All the three

Full battery-electric vehicles, hydrogen fuel-cell vehicles and fuel-cell-electric hybrid vehicles all use non-conventional propulsion instead of a pure internal-combustion engine. All three therefore qualify as alternative powertrain vehicles.

1. (a) Only one
2. (b) Only two
3. (c) All the three
4. (d) None

Answer: (d) None

Fixed-wing UAVs cannot perform vertical landing or hovering, so the claims that 'all' UAVs can do so are false. UAVs are also powered by various sources (battery, fuel engines, hybrids), not battery alone. None of the three statements is correct.

1. (a) Only one
2. (b) Only two
3. (c) Only three
4. (d) All the four

Answer: (c) Only three

In a lithium-ion cell the cathode is made from lithium combined with metals such as cobalt and nickel (and often manganese). Graphite forms the anode, not the cathode. Hence only three of the four listed elements make up the cathode.

1. (a) These are alternatives to hydrofluorocarbon refrigerants
2. (b) These are explosives in military weapons
3. (c) These are high-energy fuels for cruise missiles
4. (d) These are fuels for rocket propulsion

Answer: (b) These are explosives in military weapons

CL-20, HMX and LLM-105 are high-energy nitrogen-rich compounds developed as powerful and relatively insensitive explosives for military munitions. Their common characteristic is that they are all military explosives.

1. (a) I and II only
2. (b) II and III only
3. (c) I and III only
4. (d) I, II and III

Answer: (c) I and III only

The Majorana 1 chip is aimed at enabling scalable quantum computing, but it was unveiled by Microsoft, not Amazon Web Services, so statement II is false. Deep learning is indeed a subset of machine learning, so statements I and III are correct.

1. (a) I and II only
2. (b) II and III only
3. (c) I and III only
4. (d) I, II and III

Answer: (d) I, II and III

Monoclonal antibodies are laboratory-made proteins that bind to specific antigens and thereby modulate immune responses, and they have been used against viral diseases such as Nipah. All three statements are correct.

1. (a) Only one
2. (b) Only two
3. (c) All the three
4. (d) None

Answer: (d) None

Viruses are extremely abundant in ocean water, bacteriophages routinely infect bacteria, and many viruses alter the transcriptional activity of their host cells. Each 'no virus can...' statement is therefore false, so none of the three is correct.

1. (a) Both Statement I and Statement II are correct and Statement II explains Statement I
2. (b) Both Statement I and Statement II are correct but Statement II does not explain Statement I
3. (c) Statement I is correct but Statement II is not correct
4. (d) Statement I is not correct but Statement II is correct

Answer: (a) Both Statement I and Statement II are correct and Statement II explains Statement I

Rare earth elements are used in flat-panel television screens and computer monitors, and several of them possess phosphorescent (luminescent) properties. This phosphorescence is precisely why they are used in display phosphors, so statement II explains statement I.

1. (a) I and II only
2. (b) II and III only
3. (c) I and III only
4. (d) I, II and III

Answer: (a) I and II only

The National Rail Plan aims at a future-ready system by 2030, not 2028, so statement I is not correct, and Kavach is an indigenous Automatic Train Protection system (not developed with Germany), so statement II is not correct. Kavach does use RFID tags fixed on the track, so statement III is correct. The two incorrect statements are I and II.

1. (a) Only one
2. (b) Only two
3. (c) All the three
4. (d) None

Answer: (b) Only two

The Dornier-228 serves as a maritime patrol aircraft and the C-17 Globemaster III is a heavy military transport aircraft, so those pairs are correct. The IL-76 is a heavy-lift transport aircraft, not a supersonic combat aircraft, so that pair is wrong. Only two are correctly matched.

1. (a) silver iodide and potassium iodide
2. (b) silver nitrate and potassium iodide
3. (c) silver iodide and potassium nitrate
4. (d) silver nitrate and potassium chloride

Answer: (a) silver iodide and potassium iodide

Artificial rainfall through cloud seeding to wash out air pollution typically uses silver iodide and potassium iodide as ice-nucleating agents. These compounds provide nuclei around which water droplets condense to trigger precipitation.

1. (a) I, II and III
2. (b) II and III only
3. (c) I only
4. (d) I and II only

Answer: (d) I and II only

GAGAN augments GPS signals to provide additional accuracy and integrity and enables more uniform, high-quality air-traffic management, so statements I and II are correct. Its benefits extend beyond aviation to other transport modes and applications, so statement III is false.

1. (a) I only
2. (b) II only
3. (c) Both I and II
4. (d) Neither I nor II

Answer: (a) I only

The AI Action Summit in Paris (February 2025) was co-chaired by France and India and built upon the Bletchley Park (2023) and Seoul (2024) summits, so statement I is correct. The United States and the United Kingdom declined to sign the declaration on inclusive and sustainable AI, so statement II is false.

1. (a) Only one
2. (b) Only two
3. (c) Only three
4. (d) All four

Answer: (d) All four

Distributed Energy Resources are small-scale sources located near the point of use, and battery storage, biomass generators, fuel cells and rooftop solar PV all qualify. All four are considered DERs because they can generate or store power at the distribution level rather than at large central plants.

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

Answer: (b) 2 and 3 only

RTGs are not fission reactors; they generate electricity from the heat of radioactive decay, so statement 1 is wrong. They are used to power spacecraft onboard systems and typically use Plutonium-238, a by-product associated with weapons material, making statements 2 and 3 correct.

1. (a) Both Statement-I and Statement-II are correct and Statement-II explains Statement-I
2. (b) Both Statement-I and Statement-II are correct, but Statement-II does not explain Statement-I
3. (c) Statement-I is correct, but Statement-II is incorrect
4. (d) Statement-I is incorrect, but Statement-II is correct

Answer: (d) Statement-I is incorrect, but Statement-II is correct

Giant stars actually live much shorter lives than dwarf stars because they burn through their fuel far faster, so Statement-I is incorrect. Statement-II is correct: giant stars sustain a much greater rate of nuclear reactions, which is precisely why their lifespans are short.

1. (a) Nitric oxide
2. (b) Nitrous oxide
3. (c) Nitrogen dioxide
4. (d) Nitrogen pentoxide

Answer: (a) Nitric oxide

Nitric oxide (NO) is synthesised in the human body and acts as a signalling molecule that dilates blood vessels and increases blood flow. It should not be confused with nitrous oxide (laughing gas) or the toxic pollutants nitrogen dioxide and nitrogen pentoxide.

1. (a) Only one
2. (b) Only two
3. (c) All three
4. (d) None

Answer: (b) Only two

Radars can monitor precipitation (weather radar) and track animal migration (radar ornithology), so two of the activities apply. Detecting narcotics on passengers relies on chemical/X-ray screening, not radar, so that use does not count.

1. (a) Only one
2. (b) Only two
3. (c) All three
4. (d) None

Answer: (d) None

None of the three is a fifth-generation fighter: the Rafale is a 4.5-generation jet, the MiG-29 is fourth-generation, and the Tejas Mk-1 is a 4th/4.5-generation light fighter. True fifth-generation aircraft feature stealth and advanced sensor fusion, which these lack.

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

Answer: (a) 1 only

Hydrogels are used for controlled drug delivery in patients because their water-swollen polymer networks release medication gradually. Their listed use in mobile air-conditioning and industrial lubricants is not established, so only statement 1 applies.

1. (a) Hydrogen peroxide
2. (b) Hydronium
3. (c) Oxygen
4. (d) Water vapour

Answer: (d) Water vapour

A hydrogen fuel-cell electric vehicle combines hydrogen with oxygen to produce electricity, and its only tailpipe emission is water vapour. This zero-carbon exhaust is what makes FCEVs attractive; no hydrogen peroxide, hydronium or free oxygen is emitted.

1. (a) Irrigation of terraced crop fields
2. (b) Lift irrigation of cereal crops
3. (c) Long duration energy storage
4. (d) Rainwater harvesting system

Answer: (c) Long duration energy storage

Pumped-storage hydropower stores energy by pumping water uphill during surplus power and releasing it to generate electricity at peak demand, making it a form of long-duration energy storage. It is a grid-balancing tool, not an irrigation or rainwater-harvesting technique.

1. (a) Assisted reproductive technologies
2. (b) Drug delivery nanotechnologies
3. (c) Vaccine production technologies
4. (d) Wastewater treatment technologies

Answer: (d) Wastewater treatment technologies

Membrane bioreactors combine biological treatment with membrane filtration and are used chiefly in wastewater treatment to produce high-quality effluent. They are not associated with reproductive, drug-delivery or vaccine technologies.

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

Answer: (c) 1, 2, 3 and 4

Sustainable Aviation Fuel can be produced from a wide range of biogenic and waste feedstocks, including agricultural residues, corn grain, wastewater treatment sludge and wood mill waste. All four listed materials qualify as SAF feedstock.

1. (a) Big data analytics
2. (b) Cryptography
3. (c) Metaverse
4. (d) Virtual matrix

Answer: (c) Metaverse

The Metaverse denotes an interoperable network of persistent 3D virtual worlds accessed simultaneously by many users who can hold property rights over virtual items. Big data analytics, cryptography and 'virtual matrix' do not capture this specific meaning.

1. (a) Both Statement-I and Statement-II are correct and Statement-II is the correct explanation for Statement-I
2. (b) Both Statement-I and Statement-II are correct and Statement-II is not the correct explanation for Statement-I
3. (c) Statement-I is correct but Statement-II is incorrect
4. (d) Statement-I is incorrect but Statement-II is correct

Answer: (c) Statement-I is correct but Statement-II is incorrect

India does depend on coal for the bulk of its electricity despite holding uranium deposits, so the first statement is correct. The second is wrong because nuclear power reactors use low-enriched uranium (typically around 3-5% U-235); enrichment to 60% or more is associated with weapons-grade pathways, not electricity generation.

1. (a) Only one
2. (b) Only two
3. (c) All three
4. (d) None

Answer: (c) All three

Extremophile microbes exist for all three conditions: thermophiles/hyperthermophiles grow above 100 degrees C near hydrothermal vents, psychrophiles survive below freezing, and acidophiles thrive at pH below 3. All three statements are therefore correct.

1. (a) 1 only
2. (b) 2 only
3. (c) Both 1 and 2
4. (d) Neither 1 nor 2

Answer: (a) 1 only

Carbon fibres, prized for their high strength-to-weight ratio, are used in automobile and aircraft components, so the first statement is correct. The claim that they cannot be recycled is false, since carbon-fibre reclamation and recycling processes exist.

1. (a) Only one
2. (b) Only two
3. (c) All three
4. (d) None

Answer: (c) All three

An accelerometer detects sudden acceleration or orientation changes, so it is required in all three cases: triggering airbags in a crash, parking a laptop's hard drive during free fall, and switching a smartphone display between portrait and landscape. All three actions rely on it.

1. (a) Only one
2. (b) Only two
3. (c) All three
4. (d) None

Answer: (b) Only two

In a Recirculating Aquaculture System, biofilters treat the water by handling waste and, crucially, host nitrifying bacteria that convert toxic ammonia into nitrate, so two statements hold. They do not add phosphorus as a nutrient for fish, so that statement is false.

1. (a) Only one
2. (b) Only two
3. (c) All three
4. (d) None

Answer: (a) Only one

Only the pulsar pairing is correct: pulsars are rapidly spinning neutron stars formed when massive stars run out of fuel and collapse. Cepheids are variable stars (not dust-and-gas clouds) and nebulae are clouds of gas and dust (not periodically brightening stars), so those two pairs are mismatched.

1. (a) Australia
2. (b) Canada
3. (c) Israel
4. (d) Japan

Answer: (d) Japan

Japan operates its own regional satellite navigation system, the Quasi-Zenith Satellite System (QZSS). Australia, Canada and Israel do not maintain independent navigation constellations of their own.

1. (a) 1 only
2. (b) 2 only
3. (c) Both 1 and 2
4. (d) Neither 1 nor 2

Answer: (d) Neither 1 nor 2

Both statements are wrong: ballistic missiles are rocket-propelled and follow a ballistic trajectory (largely unpowered after boost), while cruise missiles fly powered like jets at typically subsonic-to-supersonic speeds. Agni-V is a long-range ballistic missile, and BrahMos is a supersonic cruise missile, so the descriptions are reversed.

1. (a) Only one
2. (b) Only two
3. (c) All three
4. (d) None

Answer: (c) All three

Green hydrogen can be burned directly as a fuel for internal combustion, blended with natural gas for heat or power, and used in hydrogen fuel cells to run vehicles, so all three uses are valid. It is produced by electrolysis powered by renewable energy.

1. (a) Controlling the viral diseases spread by mosquitoes
2. (b) Converting crop residues into packing material
3. (c) Producing biodegradable plastics
4. (d) Producing biochar from thermo-chemical conversion of biomass

Answer: (a) Controlling the viral diseases spread by mosquitoes

The 'Wolbachia method' involves infecting mosquitoes with Wolbachia bacteria, which suppresses their ability to transmit viruses like dengue and Zika, thereby controlling mosquito-borne viral diseases. It has nothing to do with packing material, bioplastics or biochar.

1. (a) Collecting DNA samples from air in a habitat at one go
2. (b) Understanding the genetic makeup of avian species of a habitat
3. (c) Using air-borne devices to collect blood samples from moving animals
4. (d) Sending drones to inaccessible areas to collect plant and animal samples from land surfaces and water bodies

Answer: (a) Collecting DNA samples from air in a habitat at one go

'Aerial metagenomics' refers to collecting environmental DNA present in the air of a habitat all at once, allowing scientists to detect the organisms living there without sampling them directly. It is not about avian genetics, blood sampling or drone-collected specimens.

1. (a) Studying the evolutionary relationships among various species of fauna
2. (b) Stimulating 'stem cells' to transform into diverse functional tissues
3. (c) Promoting clonal propagation of horticultural plants
4. (d) Assessing the efficacy of drugs by conducting series of drug trials in a population

Answer: (a) Studying the evolutionary relationships among various species of fauna

Microsatellite DNA (short tandem repeats) is highly variable between individuals and species and is used to study genetic diversity and evolutionary relationships among species. It is not used for stem-cell differentiation, clonal plant propagation or drug-efficacy trials.

1. (a) Only one
2. (b) Only two
3. (c) All three
4. (d) None

Answer: (c) All three

Green hydrogen can help decarbonize all three heavy industries: it can replace grey hydrogen in fertilizer (ammonia) plants and oil refineries, and serve as a reducing agent to make green steel. Each is a hard-to-abate sector where green hydrogen is expected to play a significant role.

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

Answer: (d) 1, 2, 3 and 4

Aarogya Setu, CoWIN, DigiLocker and DIKSHA are all built on open-source digital platforms, reflecting India's approach to scalable digital public infrastructure. Using open-source code allows transparency, reuse and rapid scaling, which is why all four qualify.

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

Answer: (d) 1, 2 and 3

Web 3.0 is envisioned as a decentralised internet where users control their own data (statement 1), where blockchain-based social networks can exist (statement 2), and which is run collectively by users rather than controlled by a single corporation (statement 3), so all three are correct. Decentralisation via blockchain is the defining feature distinguishing it from the corporate-platform-dominated Web 2.0.

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

Answer: (d) 1, 2 and 3

In Software as a Service, providers host applications that users access over the internet, so buyers can customise interfaces and data fields (statement 1), reach their data from mobile devices (statement 2), and web-based email services like Outlook, Hotmail and Yahoo! Mail are classic SaaS examples (statement 3). All three statements are therefore correct.

1. (a) A hypersonic missile is launched into space to counter the asteroid approaching the Earth and explode it in space.
2. (b) A spacecraft lands on another planet after making several orbital motions.
3. (c) A missile is put into a stable orbit around the Earth and deorbits over a target on the Earth.
4. (d) A spacecraft moves along a comet with the same speed and places a probe on its surface.

Answer: (c) A missile is put into a stable orbit around the Earth and deorbits over a target on the Earth.

A Fractional Orbital Bombardment System places a warhead into a low, partial orbit around the Earth and then deorbits it over a target, allowing an unpredictable approach path that can evade early-warning radars. It is a weapons-delivery concept, not an asteroid-defence, planetary-landing or comet-rendezvous mission.

1. (a) Cloud Services
2. (b) Quantum Computing
3. (c) Visible Light Communication Technologies
4. (d) Wireless Communication Technologies

Answer: (b) Quantum Computing

A qubit, or quantum bit, is the basic unit of information in quantum computing; unlike a classical bit it can exist in a superposition of 0 and 1, enabling massive parallelism. The term belongs specifically to quantum computing, not to cloud services or ordinary wireless or optical communication.

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

Answer: (d) 1, 2 and 3

Closed-circuit television, RFID and Wireless LAN all operate over limited distances, so they are all classified as short-range technologies. RFID in particular reads tags only over centimetres to a few metres, and Wi-Fi covers a local area, distinguishing them from long-range cellular or satellite links.

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

Answer: (d) 1, 2 and 3

Biofilms are communities of microbes embedded in a protective matrix, and they can form on medical implants inside body tissues (statement 1) and on food and food-processing surfaces (statement 2). The matrix shields the microbes and lets them exhibit strong antibiotic resistance (statement 3), so all three statements are correct.

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

Answer: (c) 1 and 3

Probiotics contain live beneficial organisms including both bacteria and yeast (statement 1), and they help break down milk sugars such as lactose, aiding digestion (statement 3). Statement 2 is wrong because these organisms do naturally occur in the human gut, which is precisely why supplementing them is beneficial.

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

Answer: (b) 2 and 3 only

Sputnik V uses a viral-vector platform (statement 2) and COVAXIN is an inactivated whole-virus vaccine (statement 3), so both are correct. Statement 1 is wrong because the Serum Institute's Covishield is a viral-vector vaccine (the Oxford-AstraZeneca formulation), not an mRNA vaccine.

1. (a) 1, 2, 4 and 5 only
2. (b) 2, 3, 5, 6 and 7 only
3. (c) 1, 3, 4, 6 and 7 only
4. (d) 1, 2, 3, 4, 5, 6 and 7

Answer: (c) 1, 3, 4, 6 and 7 only

A major solar storm can disrupt GPS and navigation (1), damage power grids through induced currents (3), produce widespread intense auroras (4), perturb satellite orbits by heating the upper atmosphere (6) and interrupt shortwave radio for polar flights (7). It does not cause tsunamis or trigger global forest fires, so those statements are excluded.

1. (a) 1 and 3
2. (b) 2 and 4
3. (c) 1 and 4
4. (d) 2 and 3

Answer: (a) 1 and 3

Polyethylene terephthalate fibres (polyester) can be blended with wool and cotton to strengthen fabrics (statement 1), and PET bottles are widely recycled into new products (statement 3). Statement 2 is wrong because PET is unsuitable for storing many alcoholic beverages, and statement 4 is wrong because incinerating PET releases carbon dioxide and other greenhouse gases.

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

Answer: (a) 1 and 2 only

Non-fungible tokens can digitally represent physical or digital assets (statement 1) and are unique cryptographic tokens recorded on a blockchain (statement 2). Statement 3 is wrong because, being non-fungible, each NFT is unique and cannot be exchanged at equivalence like ordinary currency, so they are not a medium of routine transactions.

1. (a) They protect the body from environmental allergens.
2. (b) They alleviate the body's pain and inflammation.
3. (c) They act as immunosuppressants in the body.
4. (d) They protect the body from the diseases caused by pathogens.

Answer: (d) They protect the body from the diseases caused by pathogens.

B cells and T cells are lymphocytes of the adaptive immune system that protect the body against diseases caused by pathogens, with B cells producing antibodies and T cells killing infected cells and coordinating immune responses. They do not primarily guard against allergens, relieve pain, or suppress immunity.

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

Answer: (d) 2 and 3

Nanoparticles of some metallic oxides such as zinc oxide and titanium dioxide are used in cosmetics like sunscreens (statement 2), and some nanoparticles from commercial products entering the environment can be unsafe for humans (statement 3). Statement 1 is wrong because nanoparticles also occur naturally, for example in volcanic ash and sea spray.

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

Answer: (d) 2 and 3

DNA barcoding compares short standardised gene sequences, which lets it distinguish species that look alike (statement 2) and detect undesirable animal or plant material in processed foods (statement 3). It cannot determine the age of an organism (statement 1), since a barcode identifies species, not individual age.

1. (a) 1 only
2. (b) 2 only
3. (c) Both 1 and 2
4. (d) Neither 1 nor 2

Answer: (c) Both 1 and 2

Recombinant vector vaccines are made using genetic engineering, in which genes coding for a pathogen's antigen are inserted into a harmless carrier, and both weakened bacteria and viruses can serve as these vectors. Both statements accurately describe the technology, so both are correct.

1. (a) 1 only
2. (b) 2 only
3. (c) Both 1 and 2
4. (d) Neither 1 nor 2

Answer: (c) Both 1 and 2

Mitochondria carry their own DNA and are inherited only from the mother (via the egg), so a child inherits mitochondrial diseases maternally, and mitochondrial replacement therapy can prevent their transmission around the time of IVF. Both statements are therefore correct.

1. (a) clonal propagation of crop plants
2. (b) developing genetically modified crop plants
3. (c) production of plant growth substances
4. (d) production of biofertilizers

Answer: (b) developing genetically modified crop plants

Bollgard I and Bollgard II are Bt cotton technologies in which genes from the bacterium Bacillus thuringiensis are inserted into cotton to make the plant resistant to bollworm pests, i.e., they are examples of developing genetically modified crops. They are not about clonal propagation, growth substances, or biofertilizers.

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

Answer: (c) 1 and 3 only

In a pressure cooker the cooking temperature depends on the internal pressure, which is set by the size of the vent hole and the weight of the pressure-regulating lid/valve, since these determine how much steam pressure builds up before release. The temperature of the flame only affects how fast pressure is reached, not the final cooking temperature, so it is not the main factor.

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

Answer: (a) 1 and 2 only

Bacteria and fungi can be grown on artificial/synthetic culture media because they are complete cells with their own metabolic machinery. Viruses are obligate intracellular parasites and require living host cells to replicate, so they cannot be cultured on lifeless synthetic media.

1. (a) 1 only
2. (b) 2 only
3. (c) Both 1 and 2
4. (d) Neither 1 nor 2

Answer: (b) 2 only

The common cold is sometimes caused by an adenovirus, while AIDS is caused by a retrovirus (HIV), making the second statement correct. Adenoviruses actually have double-stranded DNA and retroviruses have single-stranded RNA genomes, so the first statement reverses the facts and is wrong.

1. (a) it is dipolar in nature
2. (b) it is a good conductor of heat
3. (c) it has high value of specific heat
4. (d) it is an oxide of hydrogen

Answer: (a) it is dipolar in nature

Water dissolves more substances than any other liquid because its molecules are dipolar (polar), with partial positive and negative charges that pull apart and surround ionic and polar solutes. Its high specific heat or being an oxide of hydrogen does not explain its solvent power, so the dipolar nature is the key reason.

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

Answer: (c) 1 and 3 only

Sodium vapour street lamps emit light in all directions (360 degrees) while LEDs are directional, and sodium light is nearly monochromatic (yellow) whereas LEDs deliver a broader spectrum with better colour rendering. LEDs actually have a much longer lifespan than sodium lamps, so the claim that sodium lamps last longer is incorrect.

1. (a) genes introduced in the genetically modified plants
2. (b) development of India's own satellite navigation system
3. (c) radio collars for wildlife tracking
4. (d) spread of viral diseases

Answer: (d) spread of viral diseases

ACE2 (Angiotensin-Converting Enzyme 2) is a cell-surface receptor that the SARS-CoV-2 virus uses to enter human cells, so the term is discussed in the context of the spread of viral diseases. It is unrelated to GM plant genes, satellite navigation, or wildlife radio collars.

1. (a) Low-density polyethylene
2. (b) Polycarbonate
3. (c) Polyethylene terephthalate
4. (d) Polyvinyl chloride

Answer: (b) Polycarbonate

Bisphenol A (BPA) is a key structural component in the manufacture of polycarbonate plastics (used in bottles and containers) and epoxy resins, and its potential to leach out is the health concern. It is not a building block of polyethylene, PET, or PVC, so polycarbonate is the correct answer.

1. (a) Food preservatives
2. (b) Fruit-ripening substances
3. (c) Reused plastic containers
4. (d) Toiletries

Answer: (d) Toiletries

Triclosan is an antibacterial and antifungal agent commonly added to toiletries such as soaps, toothpaste, and cosmetics, raising concern over long-term exposure. It is not used as a food preservative, fruit-ripening agent, or an ingredient of plastic containers, so toiletries is the correct context.

1. (a) Distances among stellar bodies do not change.
2. (b) Gravity of stellar bodies does not change.
3. (c) Light always travels in straight line.
4. (d) Speed of light is always same.

Answer: (d) Speed of light is always same.

A light-year is a unit of distance equal to how far light travels in one year, and it is meaningful precisely because the speed of light in a vacuum is a fixed universal constant. The other options, such as light always travelling in a straight line, are not the reason such vast astronomical distances are expressed in light-years.

1. (a) fertilization of egg in vitro by the donor sperm
2. (b) genetic modification of sperm producing cells
3. (c) development of stem cells into functional embryos
4. (d) prevention of mitochondrial diseases in offspring

Answer: (d) prevention of mitochondrial diseases in offspring

Pronuclear transfer is a mitochondrial replacement technique in which the nuclear material of a fertilised egg is transferred into a donor egg with healthy mitochondria, preventing transmission of mitochondrial diseases to the offspring. It is not simple in-vitro fertilisation or sperm modification.

1. (a) 1, 2, 3 and 5 only
2. (b) 1, 3 and 4 only
3. (c) 2, 4 and 5 only
4. (d) 1, 2, 3, 4 and 5

Answer: (b) 1, 3 and 4 only

At the 2020 level of development, AI could bring down industrial electricity consumption, diagnose diseases and perform text-to-speech conversion. Wireless transmission of electrical energy is unrelated to AI, and creating genuinely meaningful short stories and songs was treated as beyond AI's effective ability, so statements 2 and 5 are excluded.

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

Answer: (c) 1, 3 and 4 only

Visible Light Communication uses the 375-780 nm visible-light band, can transmit data faster than Bluetooth and has no electromagnetic interference, making statements 1, 3 and 4 correct. VLC is a short-range technology, so statement 2 calling it long-range is wrong.

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

Answer: (d) 1 and 3 only

A blockchain is a decentralised public ledger that anyone can inspect but no single user controls, and permissionless applications can be built on its basic features, so statements 1 and 3 are correct. Blockchain data is not restricted to cryptocurrency alone, so statement 2 is wrong.

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

Answer: (c) 1, 3 and 4 only

Carbon nanotubes can carry drugs and antigens, be fashioned into artificial blood capillaries and be used in biochemical sensors, so statements 1, 2 and 3 are correct. However, carbon nanotubes are not biodegradable, which makes statement 4 wrong.

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

Answer: (d) 1, 2 and 3

Present-day drones can spray pesticides on crops, inspect the craters of active volcanoes and collect blow (breath) samples from spouting whales for DNA analysis. All three activities are technically feasible, so the fully inclusive option is correct.

1. (a) Voyager-2
2. (b) New Horizons
3. (c) LISA Pathfinder
4. (d) Evolved LISA

Answer: (d) Evolved LISA

The description of three spacecraft flying in an equilateral-triangle formation with million-kilometre sides and lasers shining between them refers to the Evolved LISA (eLISA) gravitational-wave observatory. LISA Pathfinder was only a single-spacecraft technology demonstrator for the concept.

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

Answer: (d) 1, 2 and 3

Germline editing of egg- or sperm-producing cells, editing a genome at the early embryonic stage before birth, and injecting human induced pluripotent stem cells into a pig embryo to create chimeras have all been demonstrated. Hence all three statements are correct.

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

Answer: (b) 1 and 2 only

Pneumococcal conjugate vaccines protect against pneumonia as well as meningitis and sepsis, and by preventing infection they reduce reliance on antibiotics amid rising drug resistance, so statements 1 and 2 are correct. No vaccine is entirely free of side effects or allergic reactions, so statement 3 is wrong.

1. (a) Digital security infrastructure
2. (b) Food security infrastructure
3. (c) Health care and education infrastructure
4. (d) Telecommunication and transportation infrastructure

Answer: (a) Digital security infrastructure

Public Key Infrastructure (PKI) is used in the context of digital security, underpinning digital signatures and encryption through public-private key pairs and certifying authorities. It is not related to food, health, telecom or transport infrastructure.

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

Answer: (c) 1 and 3 only

Plant cells have cellulose cell walls that animal cells lack, and a mature plant cell has one large central vacuole whereas an animal cell has several small ones, so statements 1 and 3 are correct. Both plant and animal cells possess a plasma membrane, so statement 2 is wrong.

1. (a) Some use uranium and others use thorium
2. (b) Some use imported uranium and others use domestic supplies
3. (c) Some are operated by foreign enterprises and others are operated by domestic enterprises
4. (d) Some are State-owned and others are privately-owned

Answer: (b) Some use imported uranium and others use domestic supplies

Under the civil nuclear separation plan, Indian reactors that run on imported uranium are placed under IAEA safeguards, while reactors using domestically supplied fuel need not be. The distinction is the source of the fuel, not the type of ownership or the fuel being uranium versus thorium.

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

Answer: (d) 1, 2 and 3

Steel slag, a by-product of steelmaking, can be used in the base course of roads, as a soil conditioner to improve agricultural soil, and as a raw material in cement production. All three uses are valid, so the fully inclusive option is correct.

1. (a) 1 only
2. (b) 2 only
3. (c) Both 1 and 2
4. (d) Neither 1 nor 2

Answer: (d) Neither 1 nor 2

Solar power can run both surface and submersible pumps, and it can drive both centrifugal and piston (reciprocating) pumps, since the panels simply supply electricity to the motor. Both statements are therefore false, making neither correct.

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

Answer: (b) 2 and 3 only

Only statements 2 and 3 are correct: blending hydrogen with CNG reduces carbon dioxide and hydrocarbon emissions, and hydrogen can be blended up to about one-fifth (18%) by volume. H-CNG does not fully eliminate carbon monoxide, and it is not cheaper than plain CNG.

1. (a) 1 only
2. (b) 2 only
3. (c) Both 1 and 2
4. (d) Neither 1 nor 2

Answer: (d) Neither 1 nor 2

Both statements are wrong. LTE is marketed as 4G (not 3G), and VoLTE is not a voice-only technology but a way of carrying voice as data over the LTE (4G) network. Hence neither distinction as stated is correct.

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

Answer: (b) 3 and 4

Statements 3 and 4 are correct: AR keeps the user present in the real world and enhances it (e.g. via a smartphone camera), while VR shuts out the real world and fully immerses the user. Statements 1 and 2 swap the definitions of AR and VR, so they are wrong.

1. (a) fossils of a kind of dinosaurs
2. (b) an early human species
3. (c) a cave system found in North-East India
4. (d) a geological period in the history of Indian subcontinent

Answer: (b) an early human species

'Denisovan' refers to an extinct, archaic species of early humans known mainly from fossils found in Denisova Cave in Siberia and identified through ancient DNA. They are relatives of Neanderthals and modern humans, not dinosaurs or a geological period.

1. (a) Functional chromosomes can be created by joining segments of DNA taken from cells of different species.
2. (b) Pieces of artificial functional DNA can be created in laboratories.
3. (c) A piece of DNA taken out from an animal cell can be made to replicate outside a living cell in a laboratory.
4. (d) Cells taken out from plants and animals can be made to undergo cell division in laboratory petri dishes.

Answer: (a) Functional chromosomes can be created by joining segments of DNA taken from cells of different species.

The statement that is not correct claims functional chromosomes can be created by joining DNA segments from cells of different species. The other options describe genuinely achievable feats: synthesising artificial DNA, replicating DNA outside a cell (PCR), and inducing cell division in petri dishes.

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

Answer: (c) 3 only

Only statement 3 correctly describes a digital signature: it is an electronic method of signing a document that ensures the original content is unaltered. Identifying the certifying authority and serving as proof of identity describe the digital signature certificate rather than the signature itself.

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

Answer: (d) 1, 2 and 3

All three tasks are performed by wearable devices: GPS-enabled wearables identify a person's location, fitness bands and smartwatches monitor sleep, and modern hearing aids and cochlear devices assist the hearing-impaired. Hence all three are correct.

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

Answer: (a) 1, 2 and 4

Statements 1, 2 and 4 are correct: RNА interference is used to develop gene-silencing therapies, to explore cancer treatments, and to engineer virus-resistant crop plants. It is not used to produce hormone-replacement therapies, so statement 3 is excluded.

1. (a) 'Higgs boson particles' were detected.
2. (b) 'Gravitational waves' were detected.
3. (c) Possibility of inter-galactic space travel through 'wormhole' was confirmed.
4. (d) It enabled the scientists to understand 'singularity'.

Answer: (b) 'Gravitational waves' were detected.

The observed merger of giant black holes billions of light-years away was significant because it allowed the detection of gravitational waves, ripples in space-time predicted by Einstein. This was not about Higgs bosons, wormholes or direct observation of singularity.

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

Answer: (b) 2 and 3 only

Statements 2 and 3 are the correct reasons: taking incorrect or incomplete doses of antibiotics and the widespread use of antibiotics in livestock farming drive multi-drug resistance. Genetic predisposition of people and multiple chronic diseases are not causes of resistance in pathogens.

1. (a) A molecular scissors used in targeted gene editing
2. (b) A biosensor used in the accurate detection of pathogens in patients
3. (c) A gene that makes plants pest-resistant
4. (d) A herbicidal substance synthesized in genetically modified crops

Answer: (a) A molecular scissors used in targeted gene editing

Cas9 is an enzyme that acts as 'molecular scissors' in the CRISPR-Cas9 system, cutting DNA at a targeted location to enable precise gene editing. It is not a biosensor, a pest-resistance gene, or a herbicide.

1. (a) Hepatitis B virus is transmitted much like HIV.
2. (b) Hepatitis B, unlike Hepatitis C, does not have a vaccine.
3. (c) Globally, the number of people infected with Hepatitis B and C viruses are several times more than those infected with HIV.
4. (d) Some of those infected with Hepatitis B and C viruses do not show the symptoms for many years.

Answer: (b) Hepatitis B, unlike Hepatitis C, does not have a vaccine.

The incorrect statement is that Hepatitis B, unlike Hepatitis C, has no vaccine; in fact a safe and effective Hepatitis B vaccine exists, while there is no vaccine for Hepatitis C. The other statements about transmission, greater global burden than HIV, and long asymptomatic periods are true.

1. (a) 1 only
2. (b) 2 only
3. (c) Both 1 and 2
4. (d) Neither 1 nor 2

Answer: (c) Both 1 and 2

Open APIs mean Aadhaar authentication can be built into any electronic device and any application, so statement 1 is correct, and because Aadhaar supports biometric authentication, online verification using iris (as well as fingerprint) is possible, making statement 2 correct too. This openness is what allows third parties to integrate Aadhaar-based verification.

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

Answer: (d) 1, 2 and 3

GPS provides precise positioning and, crucially, extremely accurate timing signals, so it is used in mobile-phone network synchronisation, time-stamping of banking transactions, and synchronising and controlling power grids. All three applications are valid, mainly because of GPS's role as a common time reference.

1. (a) Exoplanets
2. (b) Cryptocurrency
3. (c) Cyber attacks
4. (d) Mini satellites

Answer: (c) Cyber attacks

WannaCry and Petya are notorious ransomware programs, and EternalBlue is the exploit they used, so all three relate to cyber attacks. They have nothing to do with exoplanets, cryptocurrency or mini-satellites.

1. (a) 1 only
2. (b) 1 and 2 only
3. (c) 2 and 3 only
4. (d) None

Answer: (a) 1 only

Only statement 1 is correct: IRNSS (NavIC) uses a constellation of seven satellites—three in geostationary and four in geosynchronous orbit. Statement 2 misstates the coverage extent, and statement 3 is wrong because IRNSS is a regional system covering India and its neighbourhood, not a global navigation system.

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

Answer: (d) 1, 2 and 3

Einstein's General Theory of Relativity predicts all three: light is bent by gravity (gravitational lensing), massive objects warp the surrounding space-time, and the theory's field equations are consistent with an expanding universe. Each has since been confirmed by observation.

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

Answer: (b) 2 only

Only statement 2 is correct: GM mustard (DMH-11) carries the barnase–barstar–bar gene system that enables controlled cross-pollination and hybridisation. Statement 1 describes Bt-type pest resistance (soil-bacterium genes), which does not apply here, and statement 3 is wrong because it was developed by Delhi University's CGMCP, not by IARI and Punjab Agricultural University.

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

Answer: (b) 2 only

Only pair 2 is correct: blockchain is the technology underlying digital/cryptocurrencies. The Belle II experiment is in particle physics (not artificial intelligence) and CRISPR-Cas9 is a gene-editing tool (not particle physics), so pairs 1 and 3 are wrongly matched.

1. (a) Border Gateway Protocol
2. (b) Internet of Things
3. (c) Internet Protocol
4. (d) Virtual Private Network

Answer: (b) Internet of Things

The scenario—everyday appliances and devices sensing, communicating and acting automatically over a network—describes the Internet of Things (IoT), in which physical objects with embedded sensors exchange data. Border Gateway Protocol, Internet Protocol and Virtual Private Network are specific networking technologies, not the umbrella concept of interconnected smart devices.

1. (a) 1, 3 and 4 only
2. (b) 2, 3 and 5 only
3. (c) 1 and 4 only
4. (d) 1, 2, 3, 4 and 5

Answer: (d) 1, 2, 3, 4 and 5

3D printing (additive manufacturing) now spans all the listed fields: it is used for edible confectionery, for bio-printed structures such as bionic ears, in the automotive industry for parts and prototypes, in reconstructive surgery for implants, and it also underpins certain data-processing/electronics fabrication. Hence all five applications are valid.

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

Answer: (a) 1 only

Only statement 1 is correct: PSLVs mainly place Earth-observation satellites into polar/sun-synchronous orbits while GSLVs are meant for communication satellites in geostationary transfer orbit. Statement 2 is wrong because PSLV payloads are not geostationary, and statement 3 is wrong because GSLV Mk III is a three-stage vehicle, not four-stage.

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

Answer: (d) 1, 2, 3 and 4

Plant diseases can be spread by all four agents: birds and insects act as carriers, wind-blown dust and wind carry fungal spores and bacteria, and rain splashes and disperses pathogens between plants. Hence all of the listed factors contribute to the spread of plant diseases.

1. (a) 1 only
2. (b) 2 only
3. (c) Both 1 and 2
4. (d) Neither 1 nor 2

Answer: (c) Both 1 and 2

The Zika virus is transmitted by Aedes mosquitoes, the same vector that spreads dengue and chikungunya, so statement 1 is correct. Zika is also known to spread through sexual contact, so statement 2 is correct. Both statements are therefore true.

1. (a) Observation and understanding of the Universe
2. (b) Study of the solar and the lunar eclipses
3. (c) Placing satellites in the orbit of the Earth
4. (d) Origin and evolution of living organisms on the Earth

Answer: (a) Observation and understanding of the Universe

Terms like 'Event Horizon', 'Singularity', 'String Theory' and the 'Standard Model' belong to physics and cosmology concerned with observing and understanding the universe and its fundamental particles and forces. They are not about eclipses, satellites, or the origin of life. They span both cosmology and particle physics.

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

Answer: (d) 1, 2 and 3

Genome sequencing can identify genetic markers for disease resistance and drought tolerance, speed up the breeding of new crop varieties, and decipher host-pathogen relationships, so all three uses are valid. Reading the full DNA sequence lets breeders select desirable genes precisely. Hence statements 1, 2 and 3 are correct.

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

Answer: (d) 1, 2 and 3

Lipsticks can contain traces of lead, some soft drinks have used brominated vegetable oil as an emulsifier, and Chinese-style fast food often contains monosodium glutamate (MSG) as a flavour enhancer, so all three pairs are correctly matched. Each links a common product with a controversial chemical. Hence statements 1, 2 and 3 are correct.

1. (a) 1 and 3 only
2. (b) 2 only
3. (c) 1, 2 and 3
4. (d) None of the above statements is correct

Answer: (c) 1, 2 and 3

OLED displays are self-emissive and need no backlight, so they can be fabricated on flexible plastic substrates, embedded in roll-up form within clothing, and made transparent, giving all three advantages over LCDs. LCDs, needing a rigid backlight, cannot match this flexibility and transparency. Hence statements 1, 2 and 3 are correct.

1. (a) Production of biolarvicides
2. (b) Manufacture of biodegradable plastics
3. (c) Reproductive cloning of animals
4. (d) Production of organisms free of diseases

Answer: (c) Reproductive cloning of animals

Somatic Cell Nuclear Transfer transfers the nucleus of a body (somatic) cell into an enucleated egg, and is the technique used for reproductive cloning of animals, most famously Dolly the sheep. It is not used for making biolarvicides or biodegradable plastics. It underlies both reproductive and therapeutic cloning research.

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

Answer: (d) 1, 2 and 3

Under the IT Act and CERT-In rules, service providers, data centres and body corporates are all legally required to report cyber security incidents to CERT-In. All three categories fall under the mandatory reporting obligation. Hence statements 1, 2 and 3 are correct.

1. (a) To detect neutrinos
2. (b) To detect gravitational waves
3. (c) To detect the effectiveness of missile defence system
4. (d) To study the effect of solar flares on our communication systems

Answer: (b) To detect gravitational waves

The evolved Laser Interferometer Space Antenna (eLISA) is a planned space-based observatory designed to detect gravitational waves, the ripples in spacetime predicted by Einstein. It complements ground-based detectors like LIGO for lower-frequency waves. It is not for detecting neutrinos or missiles.

1. (a) 1 only
2. (b) 2 only
3. (c) Both 1 and 2
4. (d) Neither 1 nor 2

Answer: (c) Both 1 and 2

LiFi (Light Fidelity) uses visible light as the medium to transmit data at very high speeds. It is a wireless optical technology capable of speeds many times faster than conventional radio-based WiFi, so both statements are correct.

1. (a) Release of Neem oil in the soil increases nitrogen fixation by the soil microorganisms
2. (b) Neem coating slows down the rate of dissolution of urea in the soil
3. (c) Nitrous oxide, which is a greenhouse gas, is not at all released into atmosphere by crop fields
4. (d) It is a combination of a weedicide and a fertilizer for particular crops

Answer: (b) Neem coating slows down the rate of dissolution of urea in the soil

Neem coating on urea slows the dissolution and release of nitrogen, giving a more gradual supply that improves nitrogen-use efficiency and curbs diversion of subsidized urea to industry.

1. (a) a range of enzymes used in genome editing
2. (b) the full range of mRNA molecules expressed by an organism
3. (c) the description of the mechanism of gene expression
4. (d) a mechanism of genetic mutations taking place in cells

Answer: (b) the full range of mRNA molecules expressed by an organism

The transcriptome is the complete set of messenger RNA (mRNA) molecules expressed by a cell or organism, reflecting which genes are being actively transcribed.

1. (a) waste management technology
2. (b) wireless communication technology
3. (c) solar power production technology
4. (d) water conservation technology

Answer: (b) wireless communication technology

Project Loon uses high-altitude balloons to provide internet connectivity, making it a wireless communication technology.

1. (a) Amphibious warfare ship
2. (b) Nuclear-powered submarine
3. (c) Torpedo launch and recovery vessel
4. (d) Nuclear-powered aircraft carrier

Answer: (c) Torpedo launch and recovery vessel

INS Astradharini is an indigenously built torpedo launch and recovery vessel used by the Indian Navy for testing torpedoes and related systems.

1. (a) Electric plane tested by NASA
2. (b) Solar-powered two-seater aircraft designed by Japan
3. (c) Space observatory launched by China
4. (d) Reusable rocket designed by ISRO

Answer: (a) Electric plane tested by NASA

Greased Lightning GL-10 is an experimental electric-powered, tilt-wing unmanned aircraft tested by NASA.

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

Answer: (d) 1, 2 and 3

Viruses can infect bacteria (bacteriophages), fungi (mycoviruses) and plants, so all three groups can be infected.

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

Answer: (b) 2 and 3 only

Anyone holding a Bitcoin address can send and receive Bitcoins from any other address, and transactions can occur without either party knowing the other's real identity, so statements 2 and 3 are correct. Bitcoins are decentralized and not tracked by central banks, making statement 1 wrong.

1. (a) It can use thorium in place of uranium for power generation
2. (b) It can attain a global role in satellite navigation
3. (c) It can drastically improve the efficiency of its fission reactors in power generation
4. (d) It can build fusion reactors for power generation

Answer: (d) It can build fusion reactors for power generation

ITER is an international project to demonstrate controlled nuclear fusion; its success would allow India to build fusion reactors for power generation.

1. (a) 1 only
2. (b) 2 only
3. (c) Both 1 and 2
4. (d) Neither 1 nor 2

Answer: (c) Both 1 and 2

DigiLocker is a cloud-based digital document storage system launched under the Digital India programme, and it lets users access their e-documents from anywhere regardless of physical location. Both statements are correct.

1. (a) 1 only
2. (b) 2 only
3. (c) Both 1 and 2
4. (d) Neither 1 nor 2

Answer: (d) Neither 1 nor 2

Astrosat weighs about 1513 kg and orbits at around 650 km, not 2000 kg at 1650 km, so statement 2 is wrong. Countries and agencies other than the USA and Russia (such as ESA and Japan) have also launched space observatories, so statement 1 is wrong; neither is correct.

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

Answer: (c) 1 and 3 only

The Mangalyaan is India's Mars Orbiter Mission, and India became the only country to succeed in placing a spacecraft in Mars orbit on its very first attempt, so statements 1 and 3 are correct. India was not the second country after the USA (the USSR and ESA had also reached Mars), so statement 2 is wrong.