UPSC Prelims 2014 · Question 4 of 100

UPSC Prelims 2014 question on Steel Industry Pollutants

Which of the following are some important pollutants released by steel industry in India?

1. Oxides of sulphur
2. Oxide of nitrogen
3. Carbon monoxide
4. Carbon dioxide

Select the correct answer using the code given below.

  1. 1, 3 and 4 only
  2. 2 and 3 only
  3. 1 and 4 only
  4. 1, 2, 3 and 4
Show answer

Answer: D. 1, 2, 3 and 4

Verdict

The answer is 1, 2, 3 and 4. An integrated steel plant burns coal and coke on a very large scale, and that combustion releases all four listed gases.

Analysis

Statement 1 is CORRECT. Coal carries sulphur, so sintering and coke ovens release oxides of sulphur. Statement 2 is CORRECT. Blast furnace and reheating furnace temperatures are high enough to fix atmospheric nitrogen into oxides of nitrogen. Statement 3 is CORRECT. Carbon monoxide is not an accidental by product in ironmaking but the actual reducing agent inside the blast furnace, and some of it escapes. Statement 4 is CORRECT. Carbon dioxide is the end product of that reduction chemistry, which is why steel is among the most carbon intensive industries.

Source

International Labour Organization encyclopaedia of occupational health and safety, iron and steel chapter on environmental and public health issues.

How to crack it

When every listed item belongs to the same chemical family, ask whether one common process generates all of them. Here the single process is the combustion and coking of coal, and that answers all four statements at once. Reason from the process, not from a memorised pollutant list. The same move handles UPSC questions on thermal power, cement and brick kiln emissions, because they share the coal combustion core.

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