2013 GS Paper I, all questions

UPSC Prelims 2013 · GS Paper I

Question 8: Environment and Ecology

Which of the following can be found as pollutants in the drinking water in some parts of India?

  1. 1.Arsenic
  2. 2.Sorbitol
  3. 3.Fluoride
  4. 4.Formaldehyde
  5. 5.Uranium

Select the correct answer using the codes given below.

a1 and 3 only
b2, 4 and 5 only
c1, 3 and 5 only
d1, 2, 3, 4 and 5

AnswerUPSC’s answer is (c).

Arsenic contaminates groundwater in the Ganga-Brahmaputra plains (West Bengal, Bihar), fluoride in many dry states such as Rajasthan, and uranium has been reported in groundwater in parts of Punjab. Sorbitol is a sugar alcohol used in sweeteners and food, and formaldehyde is an industrial chemical and preservative; neither is a recognised pollutant of drinking water in India. So 1, 3 and 5 only.

  • 1. Arsenic occurs in groundwater in West Bengal, Bihar and nearby areas.
  • 2. Sorbitol is a sugar alcohol, not a water pollutant.
  • 3. Fluoride is excess in groundwater of several states.
  • 4. Formaldehyde is not a recognised drinking-water contaminant in India.
  • 5. Uranium has been reported in groundwater in parts of Punjab.

How you could have got this

  1. If you were sure statement 2 is not correct, (b) and (d) go: each of them includes 2.

    What you needed to know: Sorbitol is a sugar alcohol, not a water pollutant.

  2. Then, if you were sure statement 5 is correct, (a) goes: it leaves 5 out.

    What you needed to know: Uranium has been reported in groundwater in parts of Punjab.

Only (c) is left. You didn’t need statements 1, 3 or 4.

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) Wrong. It leaves out uranium, which has been found in groundwater in parts of India.
  • (b) Wrong. Sorbitol and formaldehyde are not recognised drinking-water pollutants here.
  • (c) Correct. Arsenic, fluoride and uranium occur in drinking water in some regions.
  • (d) Wrong. Sorbitol and formaldehyde are not drinking-water pollutants of this kind.

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

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Source: UPSC, Civil Services (Preliminary) Examination 2013, General Studies Paper I, Series A. The paper on upsc.gov.in.