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 option based on the properties and methods of colloid formation. A sol is a colloidal suspension of fine solid particles in a liquid.

### Step-by-Step Solution:

1. **Understand the Definition of a Sol**:
- A sol is a colloidal solution where solid particles are dispersed in a liquid medium. The particle size in a sol typically ranges from 1 nm to 1000 nm.

2. **Evaluate Electrophoresis**:
- Electrophoresis is the movement of dispersed particles under the influence of an electric field. This process does not create a sol; instead, it separates charged particles based on their mobility. Therefore, electrophoresis does not form a sol.

3. **Evaluate Peptidization**:
- Peptidization refers to the process of breaking down larger particles (precipitates) into smaller colloidal particles by adding an electrolyte. This process does lead to the formation of a sol, as it reduces the size of the particles into the colloidal range.

4. **Evaluate Electro Dispersion**:
- Electro dispersion (or the bis-arc method) involves creating a sol by dispersing metals like silver, platinum, or gold in a dispersion medium using an electrical spark. This method successfully forms a sol.

5. **Evaluate Colloidal Mill**:
- A colloidal mill is a mechanical device that reduces the size of solid particles to form a colloidal suspension. This method also results in the formation of a sol.

6. **Conclusion**:
- Among the methods discussed, electrophoresis is the only one that does not form a sol. Instead, it is a technique used to analyze the properties of colloidal particles.

### Final Answer:
Electrophoresis does not form a sol.

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