UPSC Prelims 2020 · GS Paper I
Question 79: Environment and Ecology
Consider the following statements :
- 1.Coal ash contains arsenic, lead and mercury.
- 2.Coal-fired power plants release sulphur dioxide and oxides of nitrogen into the environment.
- 3.High ash content is observed in Indian coal.
Which of the statements given above is/are correct ?
AnswerUPSC’s answer is (d).
Coal ash contains toxic metals such as arsenic, lead and mercury, so statement 1 is right. Coal-fired power plants release sulphur dioxide and oxides of nitrogen, so statement 2 is right. Indian coal is high in ash, commonly above 30 per cent, so statement 3 is right. All three are correct.
- 1. Coal ash contains arsenic, lead and mercury.
- 2. Coal plants emit sulphur dioxide and nitrogen oxides.
- 3. Indian coal has high ash content.
How you could have got this
- If you were sure statement 1 is correct, (b) and (c) go: each of them leaves 1 out.
What you needed to know: Coal ash contains arsenic, lead and mercury.
- Then, if you were sure statement 2 is correct, (a) goes: it leaves 2 out.
What you needed to know: Coal plants emit sulphur dioxide and nitrogen oxides.
Only (d) is left. You didn’t need statement 3.
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: statements 2 and 3 are also correct.
- (b) Wrong: statement 1 is also correct.
- (c) Wrong: statements 1 and 2 are also correct.
- (d) Right: all three are correct.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2020, General Studies Paper I, Series A. The paper on upsc.gov.in.