The acid responsible to make rain water acidic is
a) `H_(3)PO_(4)`
b) `H_(2)CO_(3)`
c) `HNO_(3)`
d) H_(2)SO_(4)`
The correct answer is

Options

A. a,b
B. a,c
C. b,c,d
D. a,c,d

Answer

To determine the acid responsible for making rainwater acidic, we need to analyze the options provided and understand the sources of acidity in rainwater.

### Step-by-Step Solution:

1. **Understanding Rainwater pH**:
- Normal rainwater has a pH of around 5.6 due to the presence of dissolved carbon dioxide, which forms carbonic acid (H₂CO₃). However, when we talk about "acid rain," the pH can drop significantly (to around 3.5) due to the presence of stronger acids.

2. **Identifying the Acids**:
- The question provides four acids:
a) H₃PO₄ (Phosphoric acid)
b) H₂CO₃ (Carbonic acid)
c) HNO₃ (Nitric acid)
d) H₂SO₄ (Sulfuric acid)

3. **Analyzing Each Acid**:
- **H₃PO₄**: While phosphoric acid can contribute to acidity, it is not a major contributor to acid rain.
- **H₂CO₃**: This is formed from carbon dioxide in the atmosphere and contributes to the natural acidity of rainwater, but it is not the primary acid responsible for acid rain.
- **HNO₃**: Nitric acid is produced from nitrogen oxides (NOx) in the atmosphere and is a significant contributor to acid rain.
- **H₂SO₄**: Sulfuric acid is formed from sulfur oxides (SOx) and is one of the main contributors to acid rain.

4. **Conclusion**:
- Among the options, both nitric acid (HNO₃) and sulfuric acid (H₂SO₄) are significant contributors to the acidity of rainwater. Therefore, the correct answer to the question is **c) HNO₃**.

### Final Answer:
The acid responsible for making rainwater acidic is **c) HNO₃ (Nitric acid)**.