Ionisation of NH_(4) OH is supressed by the addition of `NH_(4)Cl` because

Options

A. `NH_(4)CI` is a salt of WB and SA
B. `NH_(4)CI` is a salt of strong base and weak acid
C. Of the common ion effect of `NH_(4)^(+)` ion
D. None of the above

Answer

To solve the question regarding why the ionization of NH₄OH is suppressed by the addition of NH₄Cl, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Ionization of NH₄OH**:
- Ammonium hydroxide (NH₄OH) is a weak electrolyte and ionizes in solution to form ammonium ions (NH₄⁺) and hydroxide ions (OH⁻):
\[ \text{NH}_4\text{OH} \rightleftharpoons \text{NH}_4^+ + \text{OH}^- \]

2. **Effect of Adding NH₄Cl**:
- When NH₄Cl is added to the solution, it is a strong electrolyte and completely dissociates into its ions:
\[ \text{NH}_4\text{Cl} \rightarrow \text{NH}_4^+ + \text{Cl}^- \]
- This addition increases the concentration of NH₄⁺ ions in the solution.

3. **Common Ion Effect**:
- The presence of a common ion (NH₄⁺ in this case) affects the equilibrium of the ionization of NH₄OH. According to Le Chatelier's principle, if the concentration of one of the products (NH₄⁺) is increased, the equilibrium will shift to the left to counteract this change:
\[ \text{NH}_4\text{OH} \rightleftharpoons \text{NH}_4^+ + \text{OH}^- \]
- Thus, the ionization of NH₄OH is suppressed.

4. **Equilibrium Constant**:
- The equilibrium constant (K) for the ionization of NH₄OH is given by:
\[ K = \frac{[\text{NH}_4^+][\text{OH}^-]}{[\text{NH}_4\text{OH}]} \]
- With the addition of NH₄Cl, the concentration of NH₄⁺ increases, which means to maintain the value of K constant, the concentration of OH⁻ must decrease, leading to less ionization of NH₄OH.

5. **Conclusion**:
- Therefore, the ionization of NH₄OH is suppressed by the addition of NH₄Cl due to the common ion effect of NH₄⁺ ions.

### Final Answer:
The ionization of NH₄OH is suppressed by the addition of NH₄Cl because of the common ion effect of NH₄⁺ ions.

---