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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.

Defence, nuclear & energy technology questions per year: 2016: 1, 2017: 1, 2018: 1, 2019: 1, 2020: 1, 2021: 0, 2022: 0, 2023: 2, 2024: 2, 2025: 2, 2026: 4 Asked in 9 of 11 years · most in 2026 (4)

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सार्वजनिक परिवहन में बसों के लिए ईंधन के रूप में हाइड्रोजन संवर्धित CNG (H-CNG) का इस्तेमाल करने के प्रस्तावों के संदर्भ में, निम्नलिखित कथनों पर विचार कीजिए :

  1. 1.H-CNG के इस्तेमाल का मुख्य लाभ कार्बन मोनोक्साइड के उत्सर्जनों का विलोपन है।
  2. 2.ईंधन के रूप में H-CNG कार्बन डाइऑक्साइड और हाइड्रोकार्बन उत्सर्जनों को कम करती है।
  3. 3.बसों के लिए ईंधन के रूप में CNG के साथ हाइड्रोजन को आयतन के आधार पर पाँचवें हिस्से तक मिलाया जा सकता है।
  4. 4.CNG की अपेक्षा H-CNG ईंधन को कम खर्चीला बनाती है।

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

Read this question in English

In the context of proposals to the use of hydrogen-enriched CNG (H-CNG) as fuel for buses in public transport, consider the following statements:

1. The main advantage of the use of H-CNG is the elimination of carbon monoxide emissions.

2. H-CNG as fuel reduces carbon dioxide and hydrocarbon emissions.

3. Hydrogen up to one-fifth by volume can be blended with CNG as fuel for buses.

4. H-CNG makes the fuel less expensive than CNG.

Which of the statements given above is/are correct?

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

उत्तर और व्याख्या · explanation in English

Answer: (b) केवल 2 और 3

Statements 2 and 3 are correct. Blending hydrogen, which has no carbon, into CNG lowers carbon dioxide and hydrocarbon emissions, and India's trials and rules use a blend of about 18% hydrogen by volume, which is within one-fifth. H-CNG does not eliminate carbon monoxide and is not cheaper than plain CNG.

  • ✗ 1. H-CNG is still mostly natural gas, a carbon fuel, so it can lower carbon monoxide but cannot eliminate it. Official pages describe the benefit as emissions reduction, not elimination.
  • ✓ 2. Part of the fuel is carbon-free hydrogen, so less carbon is burnt per unit of energy and the blend gives lower carbon dioxide and hydrocarbon emissions; the Petroleum Ministry calls H-CNG an interim technology for emissions reduction.
  • ✓ 3. The Road Transport Ministry allowed H-CNG with an 18% hydrogen mix in CNG engines, which is under one-fifth (20%) by volume; the Delhi bus trials also used 18%.
  • ✗ 4. Making the blend is costly: the Petroleum Ministry notes that the high cost of producing and blending hydrogen offsets the fuel-economy savings over plain CNG, and its Secretary called commercial viability the main challenge.
  • • Since then After the exam year, the Road Transport Ministry notified (GSR 585(E), 25 September 2020) H-CNG with an 18% hydrogen mix as an automotive fuel.

Remember · H-CNG is CNG blended with up to about 18% hydrogen by volume: it lowers emissions but does not remove them, and it is costlier than plain CNG.

Sources

Question and answer: UPSC's official GS Paper I (2019, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). Permalink ·

हाल ही में भारत ने निम्नलिखित में से किस देश के साथ ‘नाभिकीय क्षेत्र में सहयोग क्षेत्रों के प्राथमिकीकरण और कार्यान्वयन हेतु कार्य योजना’ नामक सौदे पर हस्ताक्षर किया है?

Read this question in English

Recently, India signed a deal known as 'Action Plan for Prioritization and Implementation of Cooperation Areas in the Nuclear Field' with which of the following countries?

(a) Japan · (b) Russia · (c) The United Kingdom · (d) The United States of America

उत्तर और व्याख्या · explanation in English

Answer: (b) रूस

India signed this Action Plan with Russia during President Vladimir Putin's visit to New Delhi for the 19th annual summit, on 5 October 2018. It was signed by Rosatom, Russia's state atomic energy corporation, and India's Department of Atomic Energy.

  • ✓ (b) The India-Russia Joint Statement of 5 October 2018 records satisfaction over the signing of this Action Plan. The official list of agreements shows Rosatom's Director General and the Secretary, Department of Atomic Energy, as signatories.
  • ✗ (a) The action plan was signed with Russia, not Japan.
  • ✗ (c) The action plan was signed with Russia, not the United Kingdom.
  • ✗ (d) The action plan was signed with Russia, not the USA.

Remember · Action Plan for Prioritization and Implementation of Cooperation Areas in the Nuclear Field: India-Russia, signed 5 October 2018 (Putin's visit), between Rosatom and India's DAE.

Sources

Question and answer: UPSC's official GS Paper I (2019, 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

2 Core · 0 High · 2 Steady · 2 Rare

  • Core #45Missiles & defence technology · 7 questions
  • Core #50Energy technology: batteries, hydrogen, fusion · 6 questions

The X-Ray ranks all 928 sub-topics of the UPSC syllabus by what UPSC has asked since 2016. The 60 Prelims Core sub-topics are behind 51% of Prelims questions.

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