UPSC Prelims 2020 Q79: Environment & Ecology – Pollution & Waste Management
- (a) 1 only
- (b) 2 and 3 only
- (c) 3 only
- (d) 1, 2 and 3
Answer: (d) 1, 2 and 3
Explanation
Coal Ash: Pollutants & Environmental Impacts
| Statement | Claim | Verdict | Detail |
|---|---|---|---|
| 1 | Coal ash contains arsenic, lead, mercury | TRUE | Heavy metals concentrate in ash. Fly ash (airborne) carries toxic trace elements. |
| 2 | Coal power plants release SO2 + NOx | TRUE | Incomplete combustion produces acid rain precursors. SO2 -> sulfuric acid; NOx -> nitric acid. |
| 3 | High ash content in Indian coal | TRUE | Indian coal has 25-30% ash (vs 10-15% international average). Lignite even higher (~40%). |
All three statements are correct. Answer: (d) 1, 2 and 3.
Answer: (d) 1, 2 and 3.
Why each option is right or wrong
- (a) Incorrect. Incomplete - statements 2 and 3 also correct.
- (b) Incorrect. Statement 1 is also correct.
- (c) Incorrect. Statements 1 and 2 also correct.
- (d) CORRECT. All three statements are factually correct about coal pollution.
Key point
Coal ash impacts: Arsenic (cancer), Mercury (neurological), Lead (developmental). SO2/NOx -> acid rain (pH <5, damages crops/forests). Indian coal quality poor -> more ash/pollutants.
Remember
Coal ash contains toxic metals like arsenic, lead and mercury (Statement 1 correct). Coal-fired power plants release sulphur dioxide and oxides of nitrogen (Statement 2 correct). Indian coal has high ash content (~25-30%) compared to international standards (Statement 3 correct).
Common mistakes
- Underestimating coal toxicity. Major polluter globally (responsible for 800k+ deaths/year from air pollution).
- Assuming ash disposal is solved. India struggles with ~400M tonnes fly ash/year management.
- Missing that high ash content = more mining needed for same energy (efficiency loss).
Exam tip
Coal phase-out drivers: Pollution (arsenic, SO2, NOx, mercury), climate (CO2 emissions), water use, mining impact. India targeting 500GW renewable by 2030.
Sources
- WHO - Coal Combustion Residues and Metals
- Ministry of Power - Coal Statistics