Acid rain is caused by the pollution of environment by
Smart Elimination
Remember Acid Rain occurs when a gas (acidic) reacts with water. Thus, try to eliminate each compounds by thinking if it can form acidic by reacting with water.
• Nitrogen - Seems like a harmless/neutral compound, even used in fertilizer as a major compound. Also 78% of the air is made of Nitrogen. So not a pollutant.
• Carbon Monoxide (CO) : CO doesn't react with water and form acidic. If CO caused acid rain, big cities with traffic (high CO) should show the worst acid rain — but acid rain hotspots are industrial zones (coal power plants → Sulphur pollution).
• Ozone: Link Ozone to the Ozone layer, sounds protective and not acidic.
This understanding eliminates options (a), (b) and (c) and gives us the real culprit Nitrous Oxide and Sulphur Oxide.
Potential Trap
Confusing CO2 (Global Warming) with SO2/NOx (Acid Rain).
Answer Key & Explanation
Answer: DThe correct answer is Option D.
Explanation:
- Acid Rain is caused by the emissions of Sulphur Dioxide ($SO_2$) and Nitrogen Oxides ($NO_x$).
- These gases react with water, oxygen, and other chemicals in the atmosphere to form Sulphuric acid and Nitric acid.
- Carbon Dioxide causes ocean acidification but is not the primary component of 'Acid Rain' (which refers to pH < 5.6 due to strong acids).
Value Addition
- Taj Mahal: The yellowing of marble is due to 'Marble Cancer' caused by acid rain reacting with Calcium Carbonate.
- Sources: Burning of fossil fuels (coal plants, vehicles).
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Foundational question based on core concepts.