Miscellaneous: UPSC Previous Year Questions (Science and Technology)
2 previous year UPSC Prelims questions on Miscellaneous (Science and Technology). Choose an option to see the answer and explanation.
Explanations state facts as of the year each question was asked; words like “recently” refer to that year.
Showing 1–2 of 2 questions
UPSC 2024Science and Technology · Miscellaneous
Q1. Recently, the term "pumped-storage hydropower" is actually and appropriately discussed in the context of which one of the following?
Explanation
Pumped-storage hydropower (PSH) is primarily discussed in the context of long-duration energy storage. It is a type of hydroelectric power generation that stores excess electricity by pumping water from a lower reservoir to an upper reservoir during times of low energy demand. When energy demand is high, the stored water is released back down through turbines to generate electricity. This technology helps balance grid fluctuations, integrate renewable energy sources like wind and solar, and provide a reliable backup power supply.
UPSC 2024Science and Technology · Miscellaneous
Q2. Which one of the following is the exhaust pipe emission from Fuel Cell Electric Vehicles, powered by hydrogen?
Explanation
The exhaust pipe emission from Fuel Cell Electric Vehicles (FCEVs) powered by hydrogen is water vapour. These vehicles use hydrogen fuel cells to generate electricity through an electrochemical reaction between hydrogen and oxygen. The only by-product of this process is water (H₂O), which is released as vapour, making FCEVs a clean and environmentally friendly transportation option. Fuel cells are unique in terms of the variety of their potential applications; they can use a wide range of fuels and feedstocks and can provide power for systems as large as a utility power station and as small as a laptop computer.
Additional insight:
Working of Hydrogen Fuel Cells Simply put, fuel cells work by combining hydrogen gas (H₂) with oxygen from the air - and the resulting chemical reaction produces electricity. Hydrogen atoms enter the fuel cell at the anode, while oxygen is fed to the cathode. The fuel cell consists of a membrane coated with a catalyst. When the hydrogen molecules hit the catalyst, they’re split into hydrogen ions and electrons. The membrane lets positively charged hydrogen ions pass through, but not the negatively charged electrons, which instead flow through an electric circuit where the electric current is generated. At the cathode side, the hydrogen ions, electrons and the oxygen in the air combine to produce heat. In order to produce enough electricity to be able to propel a vehicle, a complete fuel cell system consists of several hundred membranes stacked together. The fuel cell system is adequate for normal use, but whenever extra power is needed, it’s provided by a battery on the machine. When the fuel cells produce more power than the machine currently needs, the excess energy can be used to charge the battery. The battery is also charged by regenerative braking.
Answer key for these questions
Q
UPSC year
Correct answer
1
2024
(c) Long duration energy storage
2
2024
(d) Water vapour
Frequently asked questions
How many previous year UPSC questions are there on Miscellaneous?
This page covers 2 previous year UPSC Prelims GS Paper-I questions on Miscellaneous (Science and Technology), asked from 2011 to 2025. Each has the correct answer and an explanation.
How should I use previous year UPSC questions for Prelims?
Attempt each question first, then open the answer and read the explanation for every option. Repeat by chapter, and track which statements UPSC reuses across years. Previous year questions show the exam pattern and difficulty level.
Which years are covered for Miscellaneous?
Questions on Miscellaneous (Science and Technology) are available for 15 years, from 2011 to 2025. Use the Year filter to practise a single paper.
