UPSC Prelims 2020— Question 99

This question tests coal ash and thermal power emissions. The key concept is: Coal ash can contain toxic trace elements such as arsenic, lead and mercury. Coal combustion releases sulfur dioxide and nitrogen oxides, and Indian coal is characteristically high in ash content compared with many international coals. All three statements are correct. The verified answer for the uploaded Set-B paper is option D. Option A — 1 only: This is not the correct option. The option does not match the verified combination or conclusion. The decisive point is the distinction explained above: Coal ash can contain toxic trace elements such as arsenic, lead and mercury. Coal combustion releases sulfur dioxide and nitrogen oxides, and Indian coal is characteristically high in ash content compared with many international coals. All three statements are correct. Therefore this alternative should be eliminated even if part of its wording appears plausible in isolation. Option B — 2 and 3 only: This is not the correct option. The option does not match the verified combination or conclusion. The decisive point is the distinction explained above: Coal ash can contain toxic trace elements such as arsenic, lead and mercury. Coal combustion releases sulfur dioxide and nitrogen oxides, and Indian coal is characteristically high in ash content compared with many international coals. All three statements are correct. Therefore this alternative should be eliminated even if part of its wording appears plausible in isolation. Option C — 3 only: This is not the correct option. The option does not match the verified combination or conclusion. The decisive point is the distinction explained above: Coal ash can contain toxic trace elements such as arsenic, lead and mercury. Coal combustion releases sulfur dioxide and nitrogen oxides, and Indian coal is characteristically high in ash content compared with many international coals. All three statements are correct. Therefore this alternative should be eliminated even if part of its wording appears plausible in isolation. Option D — 1, 2 and 3: This is the correct option. It matches the verified conclusion because Coal ash can contain toxic trace elements such as arsenic, lead and mercury. Coal combustion releases sulfur dioxide and nitrogen oxides, and Indian coal is characteristically high in ash content compared with many international coals. All three statements are correct. The wording of the option is consistent with the governing concept tested by the question. For UPSC-style elimination, first identify the exact proposition being tested, then evaluate each statement independently before comparing the answer codes. Avoid treating a broad or absolute statement as correct merely because its general theme is familiar. The precise qualifiers in the question—such as 'all', 'only', 'cannot', 'largest', 'always' or a specific institutional role—often determine the answer. On that basis, option D is the verified answer.