The 'acid rain' which damages historical monuments is caused mainly by the presence of

Options

A. CFCs (chloro fluoro carbons)
B. Oxides of S and N
C. `CH_(4)`
D. `CO_(2)`

Explanation

**Step-by-Step Solution:**

1. **Understanding Acid Rain**: Acid rain is a type of precipitation that is significantly more acidic than normal rainwater. It can damage buildings, monuments, and the environment.

2. **Identifying the Main Causes**: The primary components that contribute to acid rain are sulfur oxides (SOx) and nitrogen oxides (NOx), which are released into the atmosphere from various sources, including industrial processes and vehicle emissions.

3. **Chemical Reactions Involved**:
- Sulfur dioxide (SO2) can react with oxygen (O2) in the atmosphere to form sulfur trioxide (SO3).
- When sulfur trioxide reacts with water (H2O), it forms sulfuric acid (H2SO4).
- Similarly, nitrogen oxides (NOx) can react with oxygen to form nitrogen dioxide (NO2), which can further react with water to form nitric acid (HNO3).

4. **Impact on Monuments**: Historical monuments are often made of materials like marble, which is primarily composed of calcium carbonate (CaCO3).
- When acid rain (containing sulfuric and nitric acids) falls on these monuments, it reacts with calcium carbonate:
- \( \text{CaCO}_3 + \text{H}_2\text{SO}_4 \rightarrow \text{CaSO}_4 + \text{H}_2\text{O} + \text{CO}_2 \)
- This reaction leads to the corrosion of the marble, causing damage to the monuments.

5. **Conclusion**: Based on the above information, the main cause of acid rain that damages historical monuments is the presence of oxides of sulfur and nitrogen.

**Final Answer**: The 'acid rain' which damages historical monuments is caused mainly by the presence of **Oxides of Sulfur and Nitrogen** (Option B).

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