निम्नलिखित कथनों पर विचार कीजिए : कथन–I. भारत, अपने पास यूरेनियम निक्षेप (डिपॉजिट) होने के बावजूद, अपने अधिकांश विद्युत् उत्पादन के लिए कोयले पर निर्भर करता है। कथन–II. विद्युत् उत्पादन के लिए कम-से-कम 60% तक समृद्ध (एन्रिच्ड) यूरेनियम का होना आवश्यक है। उपर्युक्त कथनों के बारे में, निम्नलिखित में से कौन-सा एक सही है?

(a) कथन–I और कथन–II दोनों सही हैं तथा कथन–II, कथन–I की सही व्याख्या है

(b) कथन–I और कथन–II दोनों सही हैं तथा कथन–II, कथन–I की सही व्याख्या नहीं है

(d) कथन–I गलत है किन्तु कथन–II सही है

हरित हाइड्रोजन के संदर्भ में, निम्नलिखित कथनों पर विचार कीजिए : 1. इसे आंतरिक दहन के लिए ईंधन के रूप में सीधे इस्तेमाल किया जा सकता है। 2. इसे प्राकृतिक गैस के साथ मिलाकर ताप या शक्ति जनन के लिए ईंधन के रूप में इस्तेमाल किया जा सकता है। 3. इसे वाहन चालन के लिए हाइड्रोजन ईंधन प्रकोष्ठ में इस्तेमाल किया जा सकता है। उपर्युक्त में से कितने कथन सही हैं?

(d) कोई भी नहीं

निम्नलिखित भारी उद्योगों पर विचार कीजिए : 1. उर्वरक संयंत्र 2. तेलशोधक कारखाने 3. इस्पात संयंत्र उपर्युक्त में से कितने उद्योगों के विकार्बनन में हरित हाइड्रोजन की महत्त्वपूर्ण भूमिका होने की अपेक्षा है?

(d) कोई भी नहीं

प्रश्न यूपीएससी के हिंदी प्रश्नपत्र से · व्याख्या अभी अंग्रेज़ी में

English हिंदी

Science & technology

Prelims · Science & technology · 32 questions

Defence, nuclear & energy technology

Every UPSC Prelims question on this topic, 2016–2026, newest first. Tap an option to check yourself; the answer and explanation open below it.

Asked in 9 of 11 years · most in 2026 (4)

Practising Science & technology? Take it as timed sets of 25 →

UPSC syllabus: “General Science.” Sub-topics in the detailed syllabus →

Prelims 2023 · Q11

Easy

निम्नलिखित कथनों पर विचार कीजिए :

कथन–I: भारत, अपने पास यूरेनियम निक्षेप (डिपॉजिट) होने के बावजूद, अपने अधिकांश विद्युत् उत्पादन के लिए कोयले पर निर्भर करता है।
कथन–II: विद्युत् उत्पादन के लिए कम-से-कम 60% तक समृद्ध (एन्रिच्ड) यूरेनियम का होना आवश्यक है।

उपर्युक्त कथनों के बारे में, निम्नलिखित में से कौन-सा एक सही है?

Read this question in English

Consider the following statements:

Statement-I. India, despite having uranium deposits, depends on coal for most of its electricity production.

Statement-II. Uranium, enriched to the extent of at least 60%, is required for the production of electricity.

Which one of the following is correct in respect of the above statements?

(a) Both Statement-I and Statement-II are correct and Statement-II is the correct explanation for Statement-I · (b) Both Statement-I and Statement-II are correct and Statement-II is not the correct explanation for Statement-I · (c) Statement-I is correct but Statement-II is incorrect · (d) Statement-I is incorrect but Statement-II is correct

उत्तर और व्याख्या · explanation in English

Answer: (c) कथन–I सही है किन्तु कथन–II गलत है

Coal generates well over two-thirds of India's electricity even though the country has uranium ores, so Statement-I is right. Statement-II is wrong: India's heavy water reactors burn natural (unenriched) uranium and its light water reactors use only low-enriched uranium, nowhere near 60%.

✓ Statement-I Uranium occurs in India, for example in the Dharwar rocks and along the Singhbhum copper belt, but coal-fired plants still supply more than 70% of the electricity generated in the country.
✗ Statement-II Pressurised Heavy Water Reactors, the backbone of India's nuclear power, are fuelled by natural uranium, and Light Water Reactors by low-enriched uranium. Enrichment of 60% or more is not needed to produce electricity.

Remember · Coal: about 70–74% of India's electricity. PHWRs run on natural uranium; LWRs on low-enriched uranium. Power generation does not need highly enriched uranium.

📘 Read it in NCERT: Class 12 India: People and Economy, Ch 5 (practise this chapter)

Sources

PIB (Ministry of Coal), India's Coal Boom ↗ “The coal sector remains a crucial contributor to India’s energy mix, powering over 74% of the country’s electricity and sustaining key industries like steel and cement.”
PIB (Department of Atomic Energy), reactor fuel requirements ↗ “The Pressurised Heavy Water Reactors (PHWRs) are fuelled by Natural Uranium while Light Water Reactors (LWRs) are fuelled by Low Enriched Uranium.”
NCERT Class 12 · India: People and Economy, Chapter 5 “Important minerals used for the generation of nuclear energy are uranium and thorium. Uranium deposits occur in the Dharwar rocks.”

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2023 · Q58

X-Ray · Core #45 Easy

निम्नलिखित कथनों पर विचार कीजिए :

1.बैलिस्टिक मिसाइल अपनी पूरी उड़ान में अवध्वनिक चाल पर प्रधार-नोदित होती हैं, जबकि क्रूज़ मिसाइल केवल उड़ान के आरंभिक चरण में रॉकेट-संचालित होती हैं।
2.अग्नि-V मध्यम दूरी की पराध्वनिक क्रूज़ मिसाइल है, जबकि ब्रह्मोस ठोस ईंधन-चालित अंतरमहाद्वीपीय बैलिस्टिक मिसाइल है।

उपर्युक्त कथनों में से कौन-सा/से सही है/हैं?

Read this question in English

Consider the following statements:

1. Ballistic missiles are jet-propelled at subsonic speeds throughout their flights, while cruise missiles are rocket-powered only in the initial phase of flight.

2. Agni-V is a medium-range supersonic cruise missile, while BrahMos is a solid-fuelled intercontinental ballistic missile.

Which of the statements given above is/are correct?

(a) 1 only · (b) 2 only · (c) Both 1 and 2 · (d) Neither 1 nor 2

उत्तर और व्याख्या · explanation in English

Answer: (d) न तो 1 और न ही 2

Neither statement is correct, because both swap the facts. Ballistic missiles are rocket-boosted and then coast on an arc, while cruise missiles fly under jet power. Agni-V is India's solid-fuelled intercontinental ballistic missile, and BrahMos is a supersonic cruise missile.

✗ 1. It is reversed. A ballistic missile has a short powered boost phase and then flies a mostly unpowered ballistic path, so it is not jet-propelled throughout. A cruise missile is normally powered by jet engines for most or all of its flight.
✗ 2. Again reversed. Agni-V is a three-stage solid-propellant Inter Continental Ballistic Missile with a range of over 5,000 km. BrahMos is a long-range supersonic cruise missile, launched from land, sea or air.

Remember · Ballistic: rocket boost, then unpowered arc. Cruise: jet-powered flight in the atmosphere. Agni-V is a solid-fuelled ICBM; BrahMos is a supersonic cruise missile.

Sources

National Cruise Missile Defense: Issues and Alternatives (Congressional Budget Office, US) ↗ “almost every type fielded to date has been powered by jet engines during most or all of its flight. This has distinguished cruise missiles from ballistic missiles, which fly a mostly unpowered ballistic trajectory after an initial, relatively short, powered boost phase.”
Successful Test launch of AGNI V (Press Information Bureau, Government of India) ↗ “India successfully conducted the fourth and final experimental test of its indigenously developed Inter Continental Ballistic Missile, ICBM, Agni-V from Wheeler Island off Odisha coast”
BrahMos (Defence Research and Development Organisation, Government of India) ↗ “BRAHMOS is a universal long range supersonic cruise missile system that can be launched from land, sea and air.”

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2023 · Q60

X-Ray · Core #40 Easy

हरित हाइड्रोजन के संदर्भ में, निम्नलिखित कथनों पर विचार कीजिए :

1.इसे आंतरिक दहन के लिए ईंधन के रूप में सीधे इस्तेमाल किया जा सकता है।
2.इसे प्राकृतिक गैस के साथ मिलाकर ताप या शक्ति जनन के लिए ईंधन के रूप में इस्तेमाल किया जा सकता है।
3.इसे वाहन चालन के लिए हाइड्रोजन ईंधन प्रकोष्ठ में इस्तेमाल किया जा सकता है।

उपर्युक्त में से कितने कथन सही हैं?

Read this question in English

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?

(a) Only one · (b) Only two · (c) All three · (d) None

उत्तर और व्याख्या · explanation in English

Answer: (c) सभी तीन

All three statements are correct. Green hydrogen is hydrogen made by splitting water with renewable electricity, and it is chemically the same fuel as any other hydrogen: it can burn in an engine, be mixed into natural gas, or feed a fuel cell.

✓ 1. Hydrogen internal combustion engines are in use: India's pilot projects under the National Green Hydrogen Mission include 22 hydrogen internal-combustion vehicles.
✓ 2. Hydrogen is already being blended into gas networks in India, for example up to 8% by volume in a piped natural gas network in Surat, for use as fuel.
✓ 3. Hydrogen fuel cells power vehicles; the same pilot projects include 15 fuel-cell vehicles, and hydrogen fuel-cell buses already run in Leh and Greater Noida.

Remember · Green hydrogen (made by electrolysis with renewable power) works as engine fuel, as a blend in natural gas, and in fuel cells for vehicles.

Sources

Pilot Projects on Hydrogen Fuelled Buses and Trucks Launched under the National Green Hydrogen Mission (Press Information Bureau, MNRE) ↗ “The vehicles that will be deployed for the trial include 15 hydrogen fuel cell-based vehicles and 22 hydrogen internal combustion engine-based vehicles.”
Status of adoption of green hydrogen in the country (Press Information Bureau, MNRE) ↗ “NTPC Limited has initiated blending of Green Hydrogen up to 8% (vol/vol) in PNG Network at NTPC Kawas Township, Surat, Gujarat from January 2023.”

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

Prelims 2023 · Q99

X-Ray · Core #50 Easy

निम्नलिखित भारी उद्योगों पर विचार कीजिए :

1.उर्वरक संयंत्र
2.तेलशोधक कारखाने
3.इस्पात संयंत्र

उपर्युक्त में से कितने उद्योगों के विकार्बनन में हरित हाइड्रोजन की महत्त्वपूर्ण भूमिका होने की अपेक्षा है?

Read this question in English

Consider the following heavy industries:

1. Fertilizer plants

2. Oil refineries

3. Steel plants

Green hydrogen is expected to play a significant role in decarbonizing how many of the above industries?

(a) Only one · (b) Only two · (c) All three · (d) None

उत्तर और व्याख्या · explanation in English

Answer: (c) सभी तीन

All three. Green hydrogen, made by splitting water with renewable electricity, can replace the fossil-based hydrogen that fertilizer plants and refineries use today and the coal and coke that steel plants use for reducing iron ore. The Government of India names all three sectors in its National Green Hydrogen Mission.

✓ 1. Ammonia for nitrogenous fertilizers is made from hydrogen obtained from natural gas. Green hydrogen, or green ammonia made from it, can replace that and cut gas imports.
✓ 2. Refineries already use large amounts of hydrogen made from fossil fuels; swapping it for green hydrogen lowers a refinery's carbon footprint.
✓ 3. Hydrogen can replace coal and coke in iron and steel production, one of the biggest carbon-emitting industries; the Mission funds pilot projects for low-carbon steel.

Remember · Green hydrogen targets hard-to-abate sectors: fertilizer (green ammonia), refining, steel, and long-haul transport and shipping. India's mission aims at 5 MMT a year by 2030.

Sources

PIB, National Green Hydrogen Mission (NGHM) (Internet Archive copy) ↗ “Green Hydrogen has the potential to replace the utilization of imported fossil fuels across various sectors including fertilizer production, petroleum refining, the mobility sector, steel production and shipping propulsion applications.”
PIB, Explainer: National Hydrogen Mission (January 2023) ↗ “In industry, hydrogen can potentially replace the coal and coke in iron and steel production.”

Question and answer: UPSC's official GS Paper I (2023, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

The Syllabus X-Ray of this topic

2 of its 6 sub-topics are Core

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