(a) Only one pair
(b) Only two pairs
(c) All three pairs
(d) None of the above pairs
Relevance: This topic is highly relevant for UPSC Prelims under Science & Technology (Nuclear Energy) and India’s indigenous energy security strategy. UPSC can ask conceptual questions on India’s three-stage nuclear programme, thorium utilisation, and fast breeder reactors.
Explanation:
— STAGE 1: PHWRs use natural uranium-based fuels to generate electricity, while producing fissile plutonium (Pu239), which can be extracted by reprocessing the spent fuel. Hence, pair 1 is not correct.
— STAGE 2: FBRs of the kind at Kalpakkam, using Plutonium-based fuels, can enhance nuclear power capacity, and convert fertile thorium into fissile uranium (U233). Reprocessing of the spent fuel is vital for efficient utilisation of the plutonium inventory. Hence, pair 2 is not correct.
— STAGE 3: U233 produced in the second stage can be used for the third stage of the power programme, which consists of advanced thermal and fast breeder reactors, for long-term energy security. The use of molten salt reactors is now being seen as an option. Hence, pair 3 is correct.
Therefore, option (a) is the correct answer.
QUESTION 2
With reference to the Nipah virus, consider the following statements:
1. It is a virus found in animals but can also affect humans.
2. Fruit bats of the Pteropodidae family are the natural host of Nipah virus.
3. There is currently no treatment or vaccine available for Nipah virus.
How many of the statements given above are correct?
(a) Only one
(b) Only two
(c) All three
(d) None
Note: Earlier, in this question, statement 3 was repeated creating confusion. Now, the question has been updated and changes has been done in the question.
Relevance: UPSC frequently asks about emerging infectious diseases like Nipah virus, their natural hosts, and transmission patterns. These topics help in tackling current affairs–linked health and epidemiology questions.
Explanation:
— Nipah virus is a virus found in animals but can also affect humans. Hence, statement 1 is correct.
— People with infection can develop a fever, and symptoms involving the brain (such as headache or confusion), and/or the lungs (such as difficulty breathing or cough).
— Fruit bats of the Pteropodidae family are the natural host of Nipah virus. Nipah virus usually transmits from infected bats and other animals to humans and can also be transmitted directly between people. Hence, statement 2 is correct.
— There is currently no treatment or vaccine available for Nipah virus, however several candidate products are under development. Early intensive supportive care can improve survival. Hence, statement 3 is correct.
Therefore, option (c) is the correct answer.
(Source: http://www.who.int)
QUESTION 3
A planetary nebula is a:
(a) region of cosmic gas and dust formed from the cast-off outer layers of a dying star.
(b) dense stellar remnants formed after the explosion of a massive star in a supernova.
(c) large interstellar cloud where new stars are actively being formed.
(d) dark, cold region of space that blocks light from stars behind it.
Relevance: UPSC often asks conceptual questions distinguishing between planetary nebulae, supernovae, dark nebulae, and star-forming regions. UPSC often asks conceptual questions distinguishing between planetary nebulae, supernovae, dark nebulae, and star-forming regions.
Explanation:
— A planetary nebula marks the end of 90 per cent of all stars active lives and traces the star’s transition from a red giant to a degenerate white dwarf.
— A planetary nebula is a region of cosmic gas and dust formed by the discarded outer layers of a dying star.
— When stars of intermediate mass die, they expand to become red giants. The dying star will continue to release gas, while the surviving core of the star contracts and briefly begins to emit energy again. This energy causes the evacuated gas to ionise, which means that the gas’s atoms and molecules get charged and start emitting light. A planetary nebula is the blazing gas that has been flung off. As a result, planetary nebulae are classed as emission nebulae, which have no relation to planets.
Therefore, option (a) is the correct answer.
(Other Source: science.nasa.gov)
QUESTION 4
The ‘stick-slip’ friction refers to:
(a) frictionless motion experienced by objects in a vacuum.
(b) continuous smooth sliding motion between two lubricated surfaces.
(c) intermittent motion that occurs when two surfaces alternately stick to each other and then suddenly slip.
(d) resistance offered only by fluids to objects moving through them.
Relevance: UPSC often tests fundamental physical phenomena with real-world applications, especially concepts linked to earthquakes, machinery, and material science. Understanding terms like stick-slip helps in solving conceptual and elimination-based science MCQs.
Explanation:
— Scientists have long known that squeaking comes from what is called “stick-slip” friction. This happens when two surfaces briefly stick together and then suddenly slip apart, over and over again. These rapid cycles create vibrations in the air, which we hear as sound.
Therefore, option (c) is the correct answer.
QUESTION 5
The HTV‑X1 cargo spacecraft is an un-crewed spacecraft developed and operated by:
(a) Japan Aerospace Exploration Agency
(b) National Aeronautics and Space Administration
(c) Indian Space Research Organisation
(d) European Space Agency
Relevance: Awareness of major global space organisations and their programmes helps in eliminating close options in current affairs–based MCQs.
Explanation:
— After delivering about 12,000 pounds of supplies, scientific investigations, hardware, and other cargo to the International Space Station for NASA and its international partners, JAXA’s (Japan Aerospace Exploration Agency’s) uncrewed HTV‑X1 cargo spacecraft is scheduled to depart Friday, March 6.
— Jaxa’s spacecraft(HTV-X) is an unmanned spaceship under development to acquire a spacecraft system with the potential for improving transportation capability and operability, which can be utilized for various missions in the future, while maintaining KOUNOTORI’s superiority.
Therefore, option (a) is the correct answer.
(Source: http://www.nasa.gov, global.jaxa.jp)
Previous Daily Subject-Wise-Quiz
Daily Subject-wise quiz — History, Culture, and Social Issues (Week 147)
Daily subject-wise quiz — Polity and Governance (Week 151)
Daily subject-wise quiz — Science and Technology (Week 151)
Daily subject-wise quiz — Economy (Week 151)
Daily subject-wise quiz — Environment and Geography (Week 151)
Daily subject-wise quiz – International Relations (Week 151)
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Are you preparing for UPSC CSE Prelims 2026? Find a question on the planetary nebula in today's quiz. (Image Source: University of Manchester) 
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