Formula for degree of hydrolysis ‘h’, h `=[10^(-7)(K_aK_b)^(-1/2)]` is applicable to the salt –

Options

A. `NH_(4)CN`
B. `(NH_(4))_(2)SO_(4)`
C. `NH_(4)Cl`
D. `NH_(4)NO_(3)`

Answer

To solve the question regarding the formula for the degree of hydrolysis ‘h’ applicable to a specific salt, we will follow these steps:

### Step 1: Understand the Formula
The degree of hydrolysis 'h' is given by the formula:
\[ h = \frac{10^{-7}}{\sqrt{K_a K_b}} \]
where \( K_a \) is the acid dissociation constant and \( K_b \) is the base dissociation constant.

### Step 2: Identify the Context
This formula is applicable to salts formed from a weak acid and a weak base. The hydrolysis of such salts results in a solution that is neither strongly acidic nor strongly basic.

### Step 3: Analyze the Given Options
We need to evaluate the provided salts to determine which one is formed from a weak acid and a weak base.

1. **NH4HCN**:
- NH4+ (from NH4OH, a weak base)
- HCN (a weak acid)
- This salt is formed from a weak acid and a weak base.

2. **NH4SO4**:
- NH4+ (weak base)
- SO4^2- (from H2SO4, a strong acid)
- This salt is formed from a strong acid and a weak base.

3. **NH4Cl**:
- NH4+ (weak base)
- Cl- (from HCl, a strong acid)
- This salt is formed from a strong acid and a weak base.

4. **NH4HNO3**:
- NH4+ (weak base)
- HNO3 (a strong acid)
- This salt is formed from a strong acid and a weak base.

### Step 4: Conclusion
From the analysis, the only salt that is formed from a weak acid and a weak base is **NH4HCN**. Therefore, the formula for the degree of hydrolysis ‘h’ is applicable to this salt.

### Final Answer
The formula for the degree of hydrolysis ‘h’ is applicable to the salt **NH4HCN**.

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