What are the acids responsible for the formation of acid rain ?

Options

A. Carbonic acid only
B. Sulphuric acid and hydrofluoric acid
C. Carbonic acid and acetic acid
D. Sulphuric acid and carbonic acid

Answer

**Step-by-Step Solution:**

1. **Understanding Acid Rain**: Acid rain refers to any form of precipitation (rain, snow, sleet, or hail) that has a lower pH than that of normal rainwater. Normal rainwater has a pH of about 5.6 due to the presence of dissolved carbon dioxide, which forms carbonic acid.

2. **Identifying the Sources of Acids**: The primary acids responsible for acid rain are nitric acid (HNO₃) and sulfuric acid (H₂SO₄). These acids are formed from the reaction of nitrogen oxides (NOₓ) and sulfur oxides (SO₂) with water vapor in the atmosphere.

3. **Formation of Nitric Acid**: Nitrogen oxides (NO and NO₂) are produced from combustion processes, such as those in vehicles and power plants. When these oxides mix with water vapor in the atmosphere, they react to form nitric acid:
\[ 2NO₂ + H₂O \rightarrow HNO₃ + HNO₂ \]

4. **Formation of Sulfuric Acid**: Sulfur dioxide (SO₂) is primarily released from burning fossil fuels. When sulfur dioxide combines with water vapor, it forms sulfuric acid:
\[ SO₂ + H₂O \rightarrow H₂SO₄ \]

5. **Conclusion**: The two main acids responsible for acid rain are nitric acid (HNO₃) and sulfuric acid (H₂SO₄), which are formed from nitrogen oxides and sulfur oxides, respectively, when they react with water vapor in the atmosphere.

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