Which of the following is/are not correctly matched?

Options

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

Explanation

To determine which of the following options are not correctly matched, we will analyze each option based on the definitions of colloidal systems.

### Step-by-Step Solution:

1. **Option A: Emulsion - Curd**
- **Definition**: An emulsion is a colloidal system where two immiscible liquids are mixed, with one liquid dispersed in the other.
- **Analysis**: Curd is not an emulsion; it is a gel-like substance formed from milk. Therefore, this option is not correctly matched.

2. **Option B: Foam - Mist**
- **Definition**: Foam is a colloidal system where gas bubbles are trapped in a liquid or solid.
- **Analysis**: Mist is a colloidal system of tiny water droplets dispersed in air, which classifies it as an aerosol, not a foam. Hence, this option is also not correctly matched.

3. **Option C: Aerosol - Smoke**
- **Definition**: An aerosol is a colloidal system where the dispersion medium is gas, and the dispersed phase can be liquid or solid.
- **Analysis**: Smoke is indeed an example of an aerosol, as it consists of solid particles dispersed in air. Therefore, this option is correctly matched.

4. **Option D: Solid Sol - Cake**
- **Definition**: A solid sol is a type of colloid where solid particles are dispersed in another solid.
- **Analysis**: Cake is not an example of a solid sol; it is a mixture of various ingredients baked together. Thus, this option is not correctly matched.

### Conclusion:
The options that are not correctly matched are:
- **Option A: Emulsion - Curd**
- **Option B: Foam - Mist**
- **Option D: Solid Sol - Cake**