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 ?
- A.1 only
- B.2 and 3 only
- C.3 only
- D.1, 2 and 3
Correct answer
Explanation
The correct answer is D, 1, 2 and 3. All three statements about coal, its ash and its emissions are correct.
When coal burns in a power station, the leftover fly ash and bottom ash carry toxic heavy metals such as arsenic, lead, mercury, cadmium and chromium, which can leach into groundwater from ash ponds. The burning itself releases sulphur dioxide from the sulphur in coal and oxides of nitrogen from high-temperature combustion, both of which cause acid rain and smog; that is why flue gas desulphurisation units are being fitted. Indian coal is mostly of the Gondwana age and has a high ash content, often 30 to 45 percent, compared with about 10 to 20 percent in many imported coals, though its sulphur content is low.
A is wrong because statements 2 and 3 are also correct. B is wrong because statement 1 is also correct. C is wrong because statements 1 and 2 are also correct.
Exam tip: Indian coal = high ash, low sulphur; fly ash is used in cement and bricks.
Practice Questions
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- C.It requires shallow saltwater, not deeper than 50 metres.
- D.It requires plenty of sunlight to aid photosynthesis.
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- C.1 and 3
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Show answer
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