Which of the following cannot be hydrolysed ?

Options

A. A salt of weak acid and strong base
B. A salt of strong acid and weak base
C. A slat of weak acid and weak base
D. A salt of strong acid and strong base

Answer

To determine which of the following salts cannot be hydrolyzed, we need to understand the concept of hydrolysis and the nature of the salts formed from strong acids and strong bases.

### Step-by-Step Solution:

1. **Understanding Hydrolysis**: Hydrolysis is a chemical reaction involving the breaking down of a compound by reaction with water. In the context of salts, hydrolysis refers to the reaction of a salt with water to produce an acidic or basic solution.

2. **Identify Strong Acids and Bases**: Strong acids completely dissociate in water, and strong bases also completely dissociate. Examples include:
- Strong Acids: HCl, HNO3, H2SO4
- Strong Bases: NaOH, KOH, Ca(OH)2

3. **Formation of Neutral Salts**: When a strong acid reacts with a strong base, they form a neutral salt. For example:
- HCl (strong acid) + NaOH (strong base) → NaCl (neutral salt)

4. **Neutral Salts and Hydrolysis**: Neutral salts (formed from strong acids and strong bases) do not undergo hydrolysis because they do not produce H⁺ or OH⁻ ions in solution. This means they do not affect the pH of the solution.

5. **Examples of Salts**: Consider the following salts:
- NaCl (from HCl and NaOH)
- KBr (from HBr and KOH)
- NaNO3 (from HNO3 and NaOH)
- NH4Cl (from NH3 and HCl)

6. **Analyzing Each Salt**:
- **NaCl**: Formed from strong acid (HCl) and strong base (NaOH) - cannot be hydrolyzed.
- **KBr**: Formed from strong acid (HBr) and strong base (KOH) - cannot be hydrolyzed.
- **NaNO3**: Formed from strong acid (HNO3) and strong base (NaOH) - cannot be hydrolyzed.
- **NH4Cl**: Formed from weak base (NH3) and strong acid (HCl) - can be hydrolyzed.

7. **Conclusion**: Among the salts listed, NaCl, KBr, and NaNO3 cannot be hydrolyzed because they are formed from strong acids and strong bases. NH4Cl can be hydrolyzed because it is formed from a weak base and a strong acid.

### Final Answer:
The salts that cannot be hydrolyzed are NaCl, KBr, and NaNO3.