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Science & TechnologyHardAsked in: UPSC Civil Services · CSE Prelims 2019, GS Paper I

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

Correct answer

B. 2 and 3 only

Explanation

The correct answer is 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.

H-CNG is compressed natural gas blended with hydrogen. Because part of the fuel is hydrogen, which burns to water, less carbon is burnt per kilometre, so carbon dioxide and unburnt hydrocarbon emissions fall. Trials in India used a blend of about 18% hydrogen, which existing CNG engines can run on with small changes; Delhi tested such buses from 2020. The blend also burns more completely, cutting carbon monoxide sharply.

Statement 1 is wrong because H-CNG reduces carbon monoxide but does not eliminate it, since the fuel still contains methane. Statement 4 is wrong because hydrogen is costly to produce, so H-CNG is more expensive than plain CNG. So A (only 1), C (only 4) and D (all four) are wrong.

Exam tip: H-CNG = about 18-20% hydrogen in CNG; cuts CO2, CO and HC but costs more.

Practice Questions

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Q2.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.

Q3.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.

Q4.Science & TechnologyAsked in: CDS · CDS-II 2024, GKEasy

Mission Shakti (DRDO) of India is related to which one among the following ?

  1. A.Launch of multiple satellites using a single rocket
  2. B.Launch of heavy satellites
  3. C.Use of high power rockets in launching of satellites
  4. D.Use of rocket to destroy an orbiting satellite
Show answer
Correct answer: D. Use of rocket to destroy an orbiting satellite

Mission Shakti was India's first anti-satellite (ASAT) missile test. On 27 March 2019 DRDO fired a ground-launched interceptor from Dr. A.P.J.

Q5.Science & TechnologyAsked in: UPSC Civil Services · CSE Prelims 2016, GS Paper IMedium

Which one of the following is the best description of 'INS Astradharini', that was in the news recently?

  1. A.Amphibious warfare ship
  2. B.Nuclear-powered submarine
  3. C.Torpedo launch and recovery vessel
  4. D.Nuclear-powered aircraft carrier
Show answer
Correct answer: C. Torpedo launch and recovery vessel

INS Astradharini is an Indian Navy ship built to launch torpedoes during trials and recover them afterwards. The vessel was commissioned at Visakhapatnam in 2015.