Detailed Explanation:

Answer: Option 4 — 1, 2 and 3

All three statements about coal combustion and Indian coal characteristics are correct. Coal ash contains heavy metals, coal-fired power plants release sulfur and nitrogen oxides, and Indian coal is characterized by high ash content.

✅ Statement 1 – Correct: Coal ash, a by-product of coal combustion, contains toxic heavy metals including arsenic, lead, and mercury, which can leach into water bodies and contaminate soil, posing environmental and health hazards.

✅ Statement 2 – Correct: Coal-fired power plants release sulfur dioxide (SO₂) and nitrogen oxides (NOₓ) during combustion, which contribute to acid rain, respiratory issues, smog formation, and overall air pollution.

✅ Statement 3 – Correct: Indian coal, especially from eastern and central regions, has high ash content (30-50%), which reduces its calorific value, increases pollution levels, and results in large quantities of fly ash generation in thermal power plants.

📝 Short Notes: Coal Combustion and Environmental Impact

• Coal Ash Composition: Contains heavy metals (arsenic, lead, mercury, chromium, cadmium) that are toxic and carcinogenic; improper disposal can contaminate groundwater and soil.
• Air Pollutants from Coal Plants: Release SO₂ (causes acid rain), NOₓ (forms ground-level ozone and smog), particulate matter (PM2.5, PM10), CO₂ (greenhouse gas), and mercury emissions.
• Indian Coal Characteristics: High ash content (30-50% compared to 10-15% in imported coal), low calorific value (3000-4000 kcal/kg), and high moisture content.
• Fly Ash Utilization: India generates over 200 million tonnes of fly ash annually; used in cement manufacturing, brick making, road construction, and land filling.
• Environmental Regulations: MoEFCC mandates 100% fly ash utilization; thermal power plants must maintain electrostatic precipitators and FGD (Flue Gas Desulfurization) systems.