For the following Assertion and Reason the correct option is:
Assertion :The pH of water increases with increase in temperature
Reason : The dissociation of water into `H^(+)` and `OH^(-)` is an exothermic reaction

Options

A. Assertion is not true, but reason is true
B. Both assertion and reason are true, but the reason is not the correct explanation for the
C. Both assertion and reason are false
D. Both assertion and reason are true, and the reason the correct explanation for the assertion

Explanation

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

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "The pH of water increases with an increase in temperature."
- Normally, pure water has a pH of 7 at 25°C. As the temperature increases, the dissociation of water into hydrogen ions (H⁺) and hydroxide ions (OH⁻) occurs more readily.

2. **Effect of Temperature on Water Dissociation**:
- The dissociation of water can be represented by the equation:
\[ H_2O \rightleftharpoons H^+ + OH^- \]
- As temperature increases, the equilibrium shifts to the right, leading to an increase in the concentration of H⁺ ions.

3. **Calculating pH**:
- pH is calculated using the formula:
\[ \text{pH} = -\log[H^+] \]
- If the concentration of H⁺ ions increases, the pH value will actually decrease (not increase).

4. **Understanding the Reason**:
- The reason states that "The dissociation of water into H⁺ and OH⁻ is an exothermic reaction."
- This statement is incorrect. The dissociation of water is an endothermic process, meaning it absorbs heat. When heat is added, the reaction shifts to produce more H⁺ and OH⁻ ions.

5. **Conclusion**:
- The assertion is false because the pH of water actually decreases with an increase in temperature (it becomes more acidic).
- The reason is also false because the dissociation of water is an endothermic reaction, not exothermic.

### Final Answer:
Both the assertion and the reason are false.