Assertion (A): `pH` of `HCI` solution is less than that of acetic acid of the some concentartion.
Reason (R) : In equimolar solution, the number of titrable protons present in `HCI` is less than that present in acetic acid.

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-by-Step Solution:

1. **Understanding the Assertion (A)**:
- The assertion states that the pH of an HCl solution is less than that of an acetic acid solution of the same concentration.
- HCl is a strong acid, which means it completely dissociates in solution to produce H⁺ ions.
- Acetic acid (CH₃COOH), on the other hand, is a weak acid and only partially dissociates in solution.

2. **Comparing pH Values**:
- Since HCl completely dissociates, for a given concentration, it will produce a higher concentration of H⁺ ions compared to acetic acid.
- The pH is calculated using the formula:
\[ \text{pH} = -\log[H^+] \]
- Therefore, a higher concentration of H⁺ ions results in a lower pH value.

3. **Conclusion about Assertion (A)**:
- Since HCl produces more H⁺ ions than acetic acid at the same concentration, the pH of HCl will indeed be less than that of acetic acid.
- Thus, assertion (A) is **correct**.

4. **Understanding the Reason (R)**:
- The reason states that in equimolar solutions, the number of titratable protons present in HCl is less than that present in acetic acid.
- However, this statement is incorrect. HCl, being a strong acid, contributes more H⁺ ions compared to acetic acid, which only partially dissociates.

5. **Conclusion about Reason (R)**:
- Since HCl has more titratable protons (H⁺ ions) than acetic acid in equimolar solutions, the reason (R) is **incorrect**.

6. **Final Evaluation**:
- The assertion (A) is correct, while the reason (R) is incorrect. Therefore, the correct answer is that A is true, and R is false.

### Summary:
- Assertion (A) is correct: The pH of HCl is less than that of acetic acid at the same concentration.
- Reason (R) is incorrect: HCl has more titratable protons than acetic acid.