Which of the following solutions can act as buffer ?

Options

A. `0.1 ` molar aq. NaCl
B. `0.1` molar aq. `CH_(3)COOH + 0.1 ` M aq NaOH
C. `0.1` molar aq. Ammonium acetate
D. None of the above

Answer

To determine which of the given solutions can act as a buffer, we need to understand the criteria for a solution to function as a buffer. A buffer solution is one that can resist changes in pH upon the addition of small amounts of acids or bases. There are two types of buffer solutions:

1. **Acidic Buffer**: Formed from a weak acid and its conjugate base (which is typically a salt of the weak acid).
2. **Basic Buffer**: Formed from a weak base and its conjugate acid (which is typically a salt of the weak base).

### Step-by-Step Solution:

1. **Identify the Solutions**: We need to analyze the given solutions to see if they can form a buffer. The solutions provided are:
- 0.1 M NaCl
- 0.1 M Acetic Acid and NaOH
- 0.1 M Ammonium Acetate

2. **Analyze Each Solution**:
- **0.1 M NaCl**:
- NaCl is a salt formed from a strong acid (HCl) and a strong base (NaOH).
- Since both components are strong, this solution cannot resist pH changes and therefore cannot act as a buffer.

- **0.1 M Acetic Acid and NaOH**:
- Acetic acid (CH₃COOH) is a weak acid, and NaOH is a strong base.
- However, for a buffer to form, we need the conjugate base of acetic acid (which is acetate, CH₃COO⁻).
- Simply mixing acetic acid with NaOH does not provide the necessary conjugate base in sufficient quantity to create a buffer. Therefore, this combination does not form a buffer.

- **0.1 M Ammonium Acetate**:
- Ammonium acetate (CH₃COONH₄) is formed from a weak acid (acetic acid) and a weak base (ammonium hydroxide).
- While it contains both components, it does not fit the criteria for a buffer since both the acid and base are weak, and we need a strong acid or strong base to create a buffer system. Thus, this solution also cannot act as a buffer.

3. **Conclusion**:
- After analyzing all three solutions, we find that none of them can act as a buffer solution. Therefore, the correct answer is that none of the above can act as a buffer.

### Final Answer:
None of the above solutions can act as a buffer.