UPSC Prelims 2014 · GS Paper I
Question 24: Environment and Ecology
Which of the following are some important pollutants released by steel industry in India?
- 1.Oxides of sulphur
- 2.Oxides of nitrogen
- 3.Carbon monoxide
- 4.Carbon dioxide
Select the correct answer using the code given below.
AnswerUPSC’s answer is (d).
The steel industry burns coal and coke and uses blast furnaces, so it releases several pollutants. Sulphur in coal gives oxides of sulphur, high-temperature combustion gives oxides of nitrogen, incomplete burning of coke and in blast furnaces gives carbon monoxide, and the reduction of iron ore with carbon and combustion give carbon dioxide. All four are important pollutants from Indian steel plants.
- 1. Sulphur in coal and ore gives oxides of sulphur.
- 2. High-temperature furnaces produce oxides of nitrogen.
- 3. Blast furnaces and coke ovens emit carbon monoxide.
- 4. Burning coal and reducing ore release carbon dioxide.
How you could have got this
- If you were sure statement 1 is correct, (b) goes: it leaves 1 out.
What you needed to know: Sulphur in coal and ore gives oxides of sulphur.
- Then, if you were sure statement 2 is correct, (a) and (c) go: each of them leaves 2 out.
What you needed to know: High-temperature furnaces produce oxides of nitrogen.
Only (d) is left. You didn’t need statements 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 oxides of nitrogen, which steel plants also emit.
- (b) Wrong. Oxides of sulphur and carbon dioxide are also emitted.
- (c) Wrong. Oxides of nitrogen and carbon monoxide are also emitted.
- (d) Right. All four are released by the steel industry.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2014, General Studies Paper I, Series A. The paper on upsc.gov.in.