2012 GS Paper I, all questions

UPSC Prelims 2012 · GS Paper I

Question 12: Science and Technology

Biomass gasification is considered to be one of the sustainable solutions to the power crisis in India. In this context, which of the following statements is/are correct?

  1. 1.Coconut shells, groundnut shells and rice husk can be used in biomass gasification.
  2. 2.The combustible gases generated from biomass gasification consist of hydrogen and carbon dioxide only.
  3. 3.The combustible gases generated from biomass gasification can be used for direct heat generation but not in internal combustion engines.

Select the correct answer using the codes given below :

a1 only
b2 and 3 only
c1 and 3 only
d1, 2 and 3

AnswerUPSC’s answer is (a).

Biomass gasification converts agricultural residues such as coconut shells, groundnut shells and rice husk into producer gas by heating them with limited air. The gas is a mixture of carbon monoxide, hydrogen and methane, along with non-combustible nitrogen and carbon dioxide, so 'hydrogen and carbon dioxide only' is wrong. It can be burnt directly for heat and can also run internal combustion engines (spark-ignition or dual-fuel) to generate power.

  • 1. Coconut shells, groundnut shells and rice husk are standard gasifier feedstock.
  • 2. The combustible part is mainly carbon monoxide, hydrogen and methane; carbon dioxide does not burn.
  • 3. Producer gas can also fuel internal combustion engines to produce power.

How you could have got this

  1. If you were sure statement 3 is not correct, (b), (c) and (d) go: each of them includes 3.

    What you needed to know: Producer gas can also fuel internal combustion engines to produce power.

Only (a) is left. You didn’t need statements 1 or 2.

Which options go is worked out from UPSC’s key and the options, not by a model.

Why each option is right or wrong
  • (a) Correct: only statement 1 is right.
  • (b) Wrong: both statements 2 and 3 are false.
  • (c) Wrong: statement 3 is false, since the gas can also run internal combustion engines.
  • (d) Wrong: statements 2 and 3 are false.

Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.

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Source: UPSC, Civil Services (Preliminary) Examination 2012, General Studies Paper I, Series A. The paper on upsc.gov.in.