Assertion : Normally rain water has a pH of 5.6
Reason : `H^(+)` ions are formed by the reaction of rain water with carbon dioxide present in the air.

Options

A. If both assertion and reason are true and reason is the correct explanation of assertion.
B. If both assertion and reason are true but reason is not the c orrect explanation of assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Answer

To solve the assertion and reason question, we will analyze both statements step by step.

### Step 1: Analyze the Assertion
**Assertion:** Normally rainwater has a pH of 5.6.

- Rainwater is naturally slightly acidic due to the presence of dissolved carbon dioxide (CO2) from the atmosphere.
- When CO2 dissolves in rainwater, it reacts to form carbonic acid (H2CO3), which dissociates to release hydrogen ions (H+), contributing to the acidity of the rainwater.
- A pH of 5.6 indicates that the rainwater is indeed acidic, as a neutral pH is 7.

**Conclusion for Step 1:** The assertion is true.

### Step 2: Analyze the Reason
**Reason:** H+ ions are formed by the reaction of rainwater with carbon dioxide present in the air.

- The presence of CO2 in the atmosphere leads to the formation of carbonic acid when it dissolves in rainwater.
- The reaction can be summarized as follows:
- CO2 + H2O ⇌ H2CO3 (carbonic acid)
- H2CO3 ⇌ H+ + HCO3- (dissociation of carbonic acid)
- This process increases the concentration of H+ ions in the rainwater, thus lowering the pH.

**Conclusion for Step 2:** The reason is also true.

### Step 3: Determine the Relationship between Assertion and Reason
- Both the assertion and the reason are true.
- However, the reason does not fully explain the assertion because while it accounts for the formation of H+ ions, it does not address the complete context of why the pH is specifically 5.6, nor does it consider the influence of other factors like pollutants (e.g., SO2, NO2) that can also affect rainwater pH.

### Final Conclusion
- The assertion is true, and the reason is true, but the reason does not adequately explain the assertion. Therefore, the correct answer is that both statements are true, but the reason does not explain the assertion.