Which of the following do not show change in pH on dilution?

Options

A. 0.1 M NaCI
B. `0.1 M CH_(3)COONH_(4)`
C. `0.1 M NaHSO_(3)`
D. `NaH_(2)PO_(2)`

Answer

To determine which of the following solutions do not show a change in pH upon dilution, we need to analyze each option based on the properties of acids, bases, and salts.

### Step-by-Step Solution:

1. **Understanding pH and Dilution**:
- pH is a measure of the acidity or basicity of a solution.
- When a solution is diluted, the concentration of the solute decreases, which can affect the pH depending on the nature of the solute.

2. **Identify the Options**:
- The options given are:
- A) 0.1 mNCl (Sodium Chloride)
- B) 0.1 mCH3COOH (Acetic Acid)
- C) 0.1 mNH3 (Ammonia)
- D) NH2PO2 (Sodium Hypophosphite)

3. **Analyzing Each Option**:
- **A) 0.1 mNCl**:
- Sodium Chloride (NaCl) is a salt formed from a strong acid (HCl) and a strong base (NaOH).
- Salts of strong acids and strong bases do not change pH upon dilution.
- **Conclusion**: No change in pH.

- **B) 0.1 mCH3COOH**:
- Acetic Acid (CH3COOH) is a weak acid.
- Weak acids can change their pH upon dilution because they do not completely dissociate in solution.
- **Conclusion**: Change in pH.

- **C) 0.1 mNH3**:
- Ammonia (NH3) is a weak base.
- Weak bases can also change their pH upon dilution due to incomplete dissociation.
- **Conclusion**: Change in pH.

- **D) NH2PO2**:
- Sodium Hypophosphite is a salt formed from a weak acid (H2PO2) and a strong base (NaOH).
- Salts formed from weak acids and strong bases can change pH upon dilution.
- **Conclusion**: Change in pH.

4. **Final Evaluation**:
- From the analysis, only 0.1 mNCl (Sodium Chloride) does not show a change in pH upon dilution.
- The other options (0.1 mCH3COOH, 0.1 mNH3, and NH2PO2) will show a change in pH upon dilution.

### Final Answer:
The solution that does not show a change in pH on dilution is **0.1 mNCl (Sodium Chloride)**.