Assertion (A): `pH` of `10^(8)M HCl` is not equal to `8`.
Reason (R) : `HCl` does not dissociate properly in very dilute solution.

Options

A. If both (A) and (R) are correc, and (R) is the correct explanation of (A).
B. If both (A) and (R) are correct but (R) is not the correct explanation of (A).
C. If (A) is correct, but (R) is incorrect.
D. If (A) is incorrect, but (R) is correct.

Explanation

To solve the question, we need to analyze both the assertion (A) and the reason (R) provided.

### Step 1: Understand the Assertion (A)
The assertion states that the pH of \(10^{-8} M\) HCl is not equal to 8.

**Calculation of pH:**
1. The concentration of hydrogen ions from \(10^{-8} M\) HCl is \(10^{-8} M\).
2. However, in very dilute solutions, we also need to consider the contribution of hydrogen ions from water, which is \(10^{-7} M\) (since pure water has a pH of 7).
3. Therefore, the total concentration of hydrogen ions in the solution will be:
\[ [H^+] = 10^{-8} + 10^{-7} = 1.1 \times 10^{-7} M \]
4. Now, we can calculate the pH:
\[ pH = -\log(1.1 \times 10^{-7}) \approx 6.96 \]
This shows that the pH is not equal to 8, confirming that the assertion is correct.

### Step 2: Understand the Reason (R)
The reason states that HCl does not dissociate properly in very dilute solutions.

**Analysis of the Reason:**
1. HCl is a strong acid, which means it completely dissociates in solution regardless of its concentration.
2. Therefore, the statement that HCl does not dissociate properly in very dilute solutions is incorrect.

### Step 3: Conclusion
- The assertion (A) is correct: The pH of \(10^{-8} M\) HCl is indeed not equal to 8.
- The reason (R) is incorrect: HCl does dissociate completely in dilute solutions.

### Final Answer
Since the assertion is correct and the reason is incorrect, the correct option is **Option 3**.

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