`pK_(a)` of a weak acid `(HA)` and `pB_(b)` of a weak base `(BOH)` are 3.2 and 3.4 respectively. The `pH` of their salt (AB) solution is

Options

A. 1
B. 7.2
C. 6.9
D. 7

Explanation

To find the pH of the salt solution formed from a weak acid (HA) and a weak base (BOH), we can use the following formula:

\[ \text{pH} = \frac{1}{2} \left( pK_a + pK_b + 14 \right) \]

### Step-by-Step Solution:

1. **Identify Given Values**:
- \( pK_a \) of the weak acid \( HA = 3.2 \)
- \( pK_b \) of the weak base \( BOH = 3.4 \)

2. **Calculate \( pK_a + pK_b \)**:
\[ pK_a + pK_b = 3.2 + 3.4 = 6.6 \]

3. **Add 14 to the Sum**:
\[ pK_a + pK_b + 14 = 6.6 + 14 = 20.6 \]

4. **Divide by 2**:
\[ \frac{1}{2} (pK_a + pK_b + 14) = \frac{20.6}{2} = 10.3 \]

5. **Calculate pH**:
\[ \text{pH} = 10.3 \]

Thus, the pH of the salt solution \( AB \) is **10.3**.