The pH of ammonium phosphate solution, if `pK_(a)` of phosphoric acid and `pK_(b)` of ammonium hydroxide are 5.23 and 4.75 respectively, is _______.

Answer

To find the pH of the ammonium phosphate solution, we can use the formula for the pH of a solution formed from a weak acid and a weak base:

\[ \text{pH} = 7 + \frac{1}{2} (\text{pK}_a - \text{pK}_b) \]

### Step-by-Step Solution:

1. **Identify the Given Values:**
- \( \text{pK}_a \) of phosphoric acid = 5.23
- \( \text{pK}_b \) of ammonium hydroxide = 4.75

2. **Substitute the Values into the Formula:**
\[ \text{pH} = 7 + \frac{1}{2} (5.23 - 4.75) \]

3. **Calculate the Difference:**
\[ 5.23 - 4.75 = 0.48 \]

4. **Calculate Half of the Difference:**
\[ \frac{0.48}{2} = 0.24 \]

5. **Add this to 7:**
\[ \text{pH} = 7 + 0.24 = 7.24 \]

6. **Round to the Nearest Integer:**
Since the question asks for the nearest integer, we round 7.24 to 7.

### Final Answer:
The pH of the ammonium phosphate solution is **7**.