Question

Acid rain causes the emission of

• A. Carbon dioxide and sulphur dioxide
• B. Sulphur dioxide and carbon monoxide
• C. Sulphur dioxide and Nitrogen dioxide
• D. Sulphur dioxide and nitrous oxide

Hint:

Acid Rain Precursors: Primary gases responsible = SULPHUR DIOXIDE ($\text{SO}_2$) + NITROGEN DIOXIDE ($\text{NO}_2$), forming $\text{H}_2\text{SO}_4$ and $\text{HNO}_3$.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Atmospheric environmental pollution: acid rain ($ ext{pH} < 5.6$) is generated by the atmospheric oxidation and dissolution of precursor acidic gases, principally sulfur dioxide ($ ext{SO}_2$) and nitrogen dioxide ($ ext{NO}_2$).
Key Formula or Approach:
\[ \text{SO}_2 + \text{H}_2\text{O} \xrightarrow{\text{Oxidation}} \text{H}_2\text{SO}_4 \quad \& \quad 2\text{NO}_2 + \text{H}_2\text{O} \longrightarrow \text{HNO}_3 + \text{HNO}_2 \quad [\text{Acid Deposition}] \]

Step 2: Detailed Explanation:
In atmospheric chemistry and environmental pollution:
- Acid Rain (Acid Deposition) is caused by industrial and vehicular gaseous emissions:
1. Sulphur Dioxide ($\text{SO}_2$): Emitted primarily from coal-fired power plants and metal smelting, oxidized in the atmosphere to form sulfuric acid ($\text{H}_2\text{SO}_4$).
2. Nitrogen Dioxide ($\text{NO}_2$ $\text{NO}_x$): Emitted from internal combustion engines and fossil fuel combustion, forming nitric acid ($\text{HNO}_3$).
- When these strong acids wash down in precipitation, lake water pH drops below $5.0$, mobilizing toxic ionic aluminum ($\text{Al}^{3+}$) and causing catastrophic freshwater fish mortalities.

Step 3: Final Answer:
Thus, acid rain is associated with Sulphur dioxide and Nitrogen dioxide, corresponding to option (C).