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Science & TechnologyMediumAsked in: UPSC Civil Services · CSE Prelims 2023, GS Paper I

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?

  1. A.1 only
  2. B.2 only
  3. C.Both 1 and 2
  4. D.Neither 1 nor 2

Correct answer

D. Neither 1 nor 2

Explanation

The correct answer is D, Neither 1 nor 2. Both statements swap the features of ballistic and cruise missiles.

A ballistic missile is rocket-powered only in the first, boost phase; after that it follows a high, curved, mostly unpowered path, re-entering the atmosphere at very high speed. A cruise missile is powered by a jet engine through most of its flight and flies low and level, like an unmanned aircraft, which helps it avoid radar. Agni-V is India's solid-fuelled intercontinental-range ballistic missile with a range of over 5,000 km. BrahMos, built with Russia, is a supersonic cruise missile that flies at about Mach 2.8.

A is wrong because statement 1 reverses the two types: it is the cruise missile that is jet-propelled throughout. B is wrong because statement 2 also reverses them: Agni-V is ballistic and BrahMos is a cruise missile. C is wrong because neither statement is true.

Exam tip: Agni = ballistic (rocket boost, then free flight); BrahMos = supersonic cruise (jet-powered, low flight).

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Q1.Science & TechnologyAsked in: UPSC Civil Services · CSE Prelims 2023, GS Paper IMedium

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?

  1. A.Only one
  2. B.Only two
  3. C.All three
  4. D.None
Show answer
Correct answer: C. All three

Green hydrogen is chemically the same as any hydrogen, so it can be burnt in engines, mixed with natural gas or used in fuel cells.

Q3.Science & TechnologyAsked in: UPSC Civil Services · CSE Prelims 2017, GS Paper IMedium

With reference to agriculture in India, how can the technique of 'genome sequencing', often seen in the news, be used in the immediate future ?

1. Genome sequencing can be used to identify genetic markers for disease resistance and drought tolerance in various crop plants.

2. This technique helps in reducing the time required to develop new varieties of crop plants.

3. It can be used to decipher the host-pathogen relationships in crops.

Select the correct answer using the code given below :

  1. A.1 only
  2. B.2 and 3 only
  3. C.1 and 3 only
  4. D.1, 2 and 3
Show answer
Correct answer: D. 1, 2 and 3

Genome sequencing helps find useful genes, speeds up breeding and shows how pathogens attack crops. Genome sequencing reads the complete order of bases in an organism's DNA.

Q4.Science & TechnologyAsked in: UPSC Civil Services · CSE Prelims 2019, GS Paper IHard

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?

  1. A.1 only
  2. B.2 and 3 only
  3. C.4 only
  4. D.1, 2, 3 and 4
Show answer
Correct answer: B. 2 and 3 only

H-CNG lowers carbon dioxide and hydrocarbon emissions, and hydrogen up to about a fifth by volume can be mixed into CNG for buses.

Q5.Science & TechnologyAsked in: UPSC Civil Services · CSE Prelims 2025, GS Paper IMedium

Consider the following statements :

Statement I : Of the two major ethanol producers in the world, i.e., Brazil and the United States of America, the former produces more ethanol than the latter.

Statement II : Unlike in the United States of America where corn is the principal feedstock for ethanol production, sugarcane is the principal feedstock for ethanol production in Brazil.

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

  1. A.Both Statement I and Statement II are correct and Statement II explains Statement I
  2. B.Both Statement I and Statement II are correct but Statement II does not explain Statement I
  3. C.Statement I is correct but Statement II is not correct
  4. D.Statement I is not correct but Statement II is correct
Show answer
Correct answer: D. Statement I is not correct but Statement II is correct

The United States, not Brazil, is the world's largest ethanol producer, while the feedstocks named in Statement II are right.