Which of the following salts will not change the `pH` of pure water on dissociation?

Options

A. (a) `KCl`
B. (b) `AICl_(3)`
C. (c) `Na_(2)CO_(3)`
D. (d) `AI_(2)(SO_(4))_(3)`

Explanation

To determine which of the following salts will not change the pH of pure water upon dissociation, we need to analyze each salt based on its acidic or basic properties.

### Step-by-Step Solution:

1. **Understanding the Concept**:
- Salts are formed from the neutralization of acids and bases. The nature of the salt (acidic, basic, or neutral) depends on the strength of the acid and base from which it is derived.

2. **Analyzing Each Option**:
- **Option 1: KCl (Potassium Chloride)**:
- KCl is formed from KOH (a strong base) and HCl (a strong acid).
- Since both the acid and base are strong, KCl will dissociate in water to give K⁺ and Cl⁻ ions, which do not affect the pH.
- Therefore, KCl does not change the pH of pure water.

- **Option 2: AlCl3 (Aluminum Chloride)**:
- AlCl3 is derived from Al(OH)3 (a weak base) and HCl (a strong acid).
- When AlCl3 dissolves in water, it will produce Al³⁺ ions, which can hydrolyze to form H⁺ ions, leading to an acidic solution (pH < 7).
- Therefore, AlCl3 will change the pH of pure water.

- **Option 3: Na2CO3 (Sodium Carbonate)**:
- Na2CO3 is formed from NaOH (a strong base) and H2CO3 (a weak acid).
- Upon dissociation, Na2CO3 will produce Na⁺ and CO3²⁻ ions. The CO3²⁻ ion can react with water to produce OH⁻ ions, making the solution basic (pH > 7).
- Therefore, Na2CO3 will change the pH of pure water.

- **Option 4: Al2(SO4)3 (Aluminum Sulfate)**:
- Al2(SO4)3 is derived from Al(OH)3 (a weak base) and H2SO4 (a strong acid).
- Similar to AlCl3, the dissociation will produce Al³⁺ ions, which will lead to an acidic solution (pH < 7).
- Therefore, Al2(SO4)3 will also change the pH of pure water.

3. **Conclusion**:
- The only salt that does not change the pH of pure water upon dissociation is **KCl**.

### Final Answer:
**KCl (Potassium Chloride)** is the salt that will not change the pH of pure water on dissociation.