Consider the following: Carbon dioxide

Answer: (d) 1, 2 and 3

Burning coal oxidises its carbon to carbon dioxide. Its sulphur and the nitrogen in the fuel and combustion air form oxides of sulphur and oxides of nitrogen. All three are emitted from coal-fired thermal power plants.

• ✓ 1. Coal is mainly carbon, and burning it gives CO2 (C + O2 → CO2). NCERT lists the burning of coal as a source of carbon dioxide.
• ✓ 2. Coal combustion releases oxides of nitrogen. NCERT lists combustion of coal as a source of oxides of nitrogen. Emission standards for thermal power plants also set a limit for NOx (100 mg/Nm3).
• ✓ 3. Coal contains sulphur, so combustion emits oxides of sulphur (SO2, SO3). NCERT lists combustion of coal as a source of these oxides. Thermal power plant emission standards also limit SO2 (100 mg/Nm3).
• ✓ (d) Each of the three substances is emitted, so 'a', 'b' and 'c' are all incomplete.

Remember · Coal-fired power plants emit CO2, SO2 and NOx, plus particulate matter and mercury. SO2 and NOx cause acid rain, and CO2 is the main greenhouse gas from human activity.

📘 Read it in NCERT: Class 12 India: People and Economy, Ch 9 (practise this chapter) · Class 11 Indian Economic Development, Ch 7 (practise this chapter)

Question: UPSC Civil Services (Preliminary) 2011, General Studies Paper I. Explanation: Minimalist IAS, checked 25 Oct 2026 (how we verify). · Report an error