It takes `2.56xx10^(-3)` equivalents of `KOH` to neutralize 0.1254g `H_2 XO_4` where X is a non-metal. The number of neutrons in X are:

Options

A. 16
B. 8
C. 7
D. 32

Answer

To solve the problem, we need to determine the number of neutrons in the non-metal X in the compound \( H_2XO_4 \) given that it takes \( 2.56 \times 10^{-3} \) equivalents of KOH to neutralize \( 0.1254 \, \text{g} \) of \( H_2XO_4 \).

### Step-by-Step Solution:

1. **Identify the Acid and Its Properties**:
- The compound \( H_2XO_4 \) is an acid that can donate protons (H⁺ ions). When it dissociates, it produces 2 H⁺ ions and the anion \( XO_4^{2-} \).

2. **Determine the Moles of KOH Used**:
- Given that \( 2.56 \times 10^{-3} \) equivalents of KOH are used, and knowing that KOH has an n-factor of 1 (it provides 1 OH⁻ ion per molecule), we can directly equate equivalents to moles:
\[ \text{Moles of KOH} = 2.56 \times 10^{-3} \, \text{moles} \]

3. **Relate Moles of KOH to Moles of H⁺**:
- Since 2 moles of OH⁻ are needed to neutralize 2 moles of H⁺, the moles of H⁺ produced from \( H_2XO_4 \) will also be:
\[ \text{Moles of H}^+ = 2.56 \times 10^{-3} \, \text{moles} \]

4. **Calculate Moles of \( H_2XO_4 \)**:
- The stoichiometry of the reaction shows that 1 mole of \( H_2XO_4 \) produces 2 moles of H⁺. Therefore, the moles of \( H_2XO_4 \) can be calculated as:
\[ \text{Moles of } H_2XO_4 = \frac{2.56 \times 10^{-3}}{2} = 1.28 \times 10^{-3} \, \text{moles} \]

5. **Find Molar Mass of \( H_2XO_4 \)**:
- We know the mass of \( H_2XO_4 \) is \( 0.1254 \, \text{g} \). The molar mass (M) can be calculated using the formula:
\[ M = \frac{\text{mass}}{\text{moles}} = \frac{0.1254 \, \text{g}}{1.28 \times 10^{-3} \, \text{moles}} \approx 97.96 \, \text{g/mol} \]

6. **Set Up the Equation for Molar Mass**:
- The molar mass of \( H_2XO_4 \) can be expressed as:
\[ 2 \times 1 + x + 4 \times 16 = 98 \]
- Simplifying gives:
\[ 2 + x + 64 = 98 \implies x + 66 = 98 \implies x = 32 \, \text{g/mol} \]
- Here, \( x \) is the molar mass of the non-metal X.

7. **Identify the Non-Metal X**:
- The atomic mass of 32 g/mol corresponds to sulfur (S), which has an atomic number of 16.

8. **Calculate the Number of Neutrons**:
- The number of neutrons can be calculated using the formula:
\[ \text{Number of Neutrons} = \text{Mass Number} - \text{Atomic Number} \]
- For sulfur:
\[ \text{Mass Number} = 32, \quad \text{Atomic Number} = 16 \]
- Therefore:
\[ \text{Number of Neutrons} = 32 - 16 = 16 \]

### Final Answer:
The number of neutrons in X is **16**.