UPSC CSE (Preliminary) Exam 2024 Paper I (GS) – 16 June 2024 (Answer Key)

Explanation –

• Statement 1 is incorrect: RTGs are not miniature fission reactors; they use the decay of radioactive isotopes to generate electricity.
• Statement 2 is correct: RTGs are used for powering the onboard systems of spacecraft.
• Statement 3 is correct: RTGs can use Plutonium-238, which is a by-product of weapons development.

Explanation –

• Statement I is incorrect: Giant stars live shorter lives than dwarf stars due to their higher rates of nuclear fusion.
• Statement II is correct: Giant stars have a greater rate of nuclear reactions compared to dwarf stars.

Explanation –

• Option (a) is correct: Nitric oxide is synthesized in the human body and acts as a vasodilator, increasing blood flow.
• Option (b) is incorrect: Nitrous oxide is a gas used for anesthesia and pain relief, not involved in vasodilation.
• Option (c) is incorrect: Nitrogen dioxide is a toxic gas, not involved in vasodilation.
• Option (d) is incorrect: Nitrogen pentoxide is a chemical compound, not involved in vasodilation.

Explanation –

• Statement 1 is incorrect: Radars are not used for identifying narcotics on passengers at airports or in aircraft.
• Statement 2 is correct: Radars can be used for monitoring precipitation.
• Statement 3 is correct: Radars can be used for tracking the migration of animals.

Explanation –

• Option (a) is incorrect: Rafael is a fourth-generation fighter aircraft.
• Option (b) is incorrect: MiG-29 is a fourth-generation fighter aircraft.
• Option (c) is incorrect: Tejas MK-1 is a fourth-generation fighter aircraft.
• Option (d) is correct: None of the listed aircraft are fifth-generation fighter aircraft.

Explanation – 

• Option (a) is correct: Hydrogels are used for controlled drug delivery in patients.
• Option (b) is correct: Hydrogels are used in mobile air-conditioning systems for cooling purposes.
• Option (c) is correct: Hydrogels are used in the preparation of industrial lubricants.

Explanation –

• Fuel cell electric vehicles (FCEVs) are powered by hydrogen. They are more efficient than conventional internal combustion engine vehicles and produce no harmful tailpipe emissions—they only emit water vapor and warm air.
• FCEVs use a propulsion system similar to that of electric vehicles, where energy stored as hydrogen is converted to electricity by the fuel cell. Unlike conventional internal combustion engine vehicles, these vehicles produce no harmful tailpipe emissions.
• FCEVs are fueled with pure hydrogen gas stored in a tank on the vehicle. Similar to conventional internal combustion engine vehicles, they can fuel in about 5 minutes and have a driving range of more than 300 miles. FCEVs are equipped with other advanced technologies to increase efficiency, such as regenerative braking systems that capture the energy lost during braking and store it in a battery.

Explanation – Pumped storage hydropower is a form of clean energy storage that is ideal for electricity grids reliant on solar and wind power. The technology absorbs surplus energy at times of low demand and releases it when demand is high. Thus, facilitates long duration energy storage.

Explanation –  Membrane bioreactor (MBR) technology has emerged as a wastewater treatment technology of choice over the activated sludge process (ASP), which has been the conventional municipal wastewater technology over the last century.

Explanation – CBLO is a money market instrument that represents an obligation between a borrower and a lender. The instrument works like a bond where the lender buys the CBLO and a borrower sells the money market instrument with interest.