A buffer solution can be prepared from a mixture of
1. Sodium acetate and acetic acid in water
2. Excess sodium acetate and hydrochloric acid in water
3. Ammonia and ammonia chloride in water
4. Ammonia and sodium hydroxide in water.

Options

A. 1,3,4
B. 2,3,4
C. 1,2,4
D. 1,3

Answer

To determine which of the given mixtures can form a buffer solution, we need to understand the concept of buffer solutions. A buffer solution is a system that can resist changes in pH upon the addition of small amounts of an acid or a base. There are two types of buffer solutions:

1. **Acidic Buffer**: Formed from a weak acid and its salt (which is derived from a strong base).
2. **Basic Buffer**: Formed from a weak base and its salt (which is derived from a strong acid).

Now, let's analyze each option provided in the question:

### Step-by-Step Solution:

1. **Option 1: Sodium acetate and acetic acid in water**
- Sodium acetate (CH₃COONa) is the salt of acetic acid (CH₃COOH), which is a weak acid. This combination can form an acidic buffer solution.
- **Conclusion**: This option can form a buffer solution.

2. **Option 2: Excess sodium acetate and hydrochloric acid in water**
- Sodium acetate (CH₃COONa) is a salt of acetic acid, and hydrochloric acid (HCl) is a strong acid. The presence of excess sodium acetate means that acetic acid will be produced when HCl reacts with sodium acetate.
- The resulting mixture will contain acetic acid and its salt (sodium acetate), which can also function as an acidic buffer.
- **Conclusion**: This option can form a buffer solution.

3. **Option 3: Ammonia and ammonium chloride in water**
- Ammonia (NH₃) is a weak base, and ammonium chloride (NH₄Cl) is the salt of ammonium (NH₄⁺), which is derived from a strong acid (HCl). This combination can form a basic buffer solution.
- **Conclusion**: This option can form a buffer solution.

4. **Option 4: Ammonia and sodium hydroxide in water**
- Ammonia (NH₃) is a weak base, but sodium hydroxide (NaOH) is a strong base. The presence of a strong base does not allow the formation of a buffer solution because it will not resist changes in pH effectively.
- **Conclusion**: This option cannot form a buffer solution.

### Final Answer:
The mixtures that can form buffer solutions are:
- **Option 1**: Sodium acetate and acetic acid in water
- **Option 2**: Excess sodium acetate and hydrochloric acid in water
- **Option 3**: Ammonia and ammonium chloride in water

**Therefore, the correct answer is Options 1, 2, and 3.**