Which of the following does not form a sol?

Options

A. Electrophoresis
B. Peptization
C. Electrodispersion
D. Colloidal mill

Answer

To determine which of the following does not form a sol, we need to analyze each of the given processes and understand their roles in colloid formation.

### Step-by-Step Solution:

1. **Understanding Electrophoresis**:
- Electrophoresis is the process where charged particles migrate under the influence of an electric field.
- In this process, ions or charged particles move towards the electrode of opposite charge (anode or cathode) without forming a colloidal solution.
- **Conclusion**: Electrophoresis does not lead to the formation of a sol.

2. **Understanding Peptization**:
- Peptization is the process of converting a precipitate into a colloidal sol by using a peptizing agent or suitable electrolyte.
- This process results in the formation of a colloid.
- **Conclusion**: Peptization does form a sol.

3. **Understanding Electrode Dispersion**:
- Electrode dispersion (or the arc method) involves striking an electric arc between electrodes, which generates heat that vaporizes the metal.
- The vaporized metal condenses in a cold bath to form colloidal particles.
- **Conclusion**: Electrode dispersion does form a sol.

4. **Understanding Colloidal Mill**:
- A colloidal mill is a machine that reduces the particle size of a suspension to the colloidal range.
- This process also leads to the formation of colloidal particles.
- **Conclusion**: A colloidal mill does form a sol.

### Final Answer:
Based on the analysis, the process that does not form a sol is **Electrophoresis**.