Which one of the following is correctly matched?

Options

A. Emulsion - Curd
B. Foam - mist
C. Aerosol - smoke
D. Solid sol - Butter

Answer

To determine which of the following options is correctly matched regarding colloids, we need to analyze the examples provided and their classifications.

### Step-by-Step Solution:

1. **Understand the Types of Colloids**:
- Colloids are mixtures where one substance (the dispersed phase) is distributed evenly throughout another substance (the continuous phase).
- Common types of colloids include emulsions, foams, aerosols, and sols.

2. **Analyze Each Option**:
- **Option 1: Emulsion** - An emulsion is a colloid where both phases are liquids. For example, oil in water is an emulsion. The mention of curd is incorrect here as curd is not a simple emulsion; it is a complex mixture of proteins and fats.
- **Option 2: Foam** - Foam is a colloid where gas is dispersed in a liquid. The example given is mist, which is incorrect. Mist is actually a colloid of liquid droplets in air (aerosol), not gas in liquid.
- **Option 3: Aerosol** - An aerosol consists of tiny solid or liquid particles dispersed in a gas. Examples include fog and smog, which are indeed aerosols. This option is correctly matched.
- **Option 4: Sol** - A sol is a colloid where solid particles are dispersed in a liquid. The description provided seems to confuse the definitions, as it does not correctly represent a sol.

3. **Conclusion**:
- After analyzing the definitions and examples, we find that **Option 3 (Aerosol)** is the only correctly matched example.

### Final Answer:
The correctly matched option is **Aerosol**.