Which one of the following is correctly matched?

Options

A. Emulsion - curd
B. Foam - mist
C. Aerosol - smoke
D. Solid sol - cake

Explanation

To determine which of the given options is correctly matched, we need to analyze each option based on the definitions of colloidal systems. Here’s a step-by-step breakdown:

### Step 1: Understand the Types of Colloids
Colloids can be classified based on the states of the dispersed phase and the dispersion medium. The main types include:
- **Emulsion**: Dispersed phase and dispersion medium are both liquids.
- **Foam**: Dispersed phase is gas, and dispersion medium is liquid.
- **Aerosol**: Dispersed phase can be solid or liquid, and dispersion medium is gas.
- **Solid Foam**: Dispersed phase is gas, and dispersion medium is solid.
- **Solid Sol**: Both dispersed phase and dispersion medium are solid.

### Step 2: Analyze Each Option
1. **Emulsion - Curd**:
- Curd is a colloidal solution where the dispersed phase is solid (casein proteins) and the dispersion medium is liquid (water).
- **Conclusion**: This is incorrectly matched as emulsion requires both phases to be liquid.

2. **Foam - Mist**:
- Mist is a colloidal system where the dispersed phase is liquid (water droplets) and the dispersion medium is gas (air).
- **Conclusion**: This is incorrectly matched as foam requires the dispersed phase to be gas.

3. **Aerosol - Smoke**:
- Smoke is a colloidal system where the dispersed phase is solid (soot particles) and the dispersion medium is gas (air).
- **Conclusion**: This is correctly matched as smoke is indeed a solid aerosol.

4. **Solid Sol - Cake**:
- Cake is a colloidal system where the dispersed phase is gas (air pockets) and the dispersion medium is solid (the cake itself).
- **Conclusion**: This is incorrectly matched as solid sol requires both phases to be solid.

### Step 3: Identify the Correct Match
From the analysis, the only correctly matched option is:
- **Aerosol - Smoke** (Option 3).

### Final Answer
The correctly matched option is **Aerosol - Smoke**.

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