When a small quantity of `FeCl_(3)` solution is added to the fresh precipitate of `Fe(OH)_(3)` , a colloidal sol is obtained. The process through which this sol is formed is known as

Options

A. exchange of solvent
B. chemical double decomposition
C. peptization
D. electrophoresis

Explanation

To solve the question, we need to identify the process that occurs when a small quantity of FeCl₃ solution is added to a fresh precipitate of Fe(OH)₃, resulting in the formation of a colloidal sol.

### Step-by-Step Solution:

1. **Understanding the Components**:
- We have a precipitate of Fe(OH)₃, which is a solid formed when iron(III) ions react with hydroxide ions.
- When we add FeCl₃ (iron(III) chloride) solution to this precipitate, we need to analyze what happens next.

2. **Identifying the Process**:
- The addition of FeCl₃ introduces iron(III) ions into the system. These ions can interact with the Fe(OH)₃ precipitate.
- The process of converting a precipitate into a colloidal solution typically involves the dispersion of the solid particles into the liquid phase.

3. **Recognizing Peptization**:
- The specific process that describes the conversion of a precipitate into a colloidal sol by adding an electrolyte (like FeCl₃) is known as **peptization**.
- In peptization, the precipitate is shaken with a dispersion medium (the liquid in which it is suspended) in the presence of a small amount of an electrolyte, which helps to stabilize the colloidal particles.

4. **Conclusion**:
- Therefore, when FeCl₃ is added to the Fe(OH)₃ precipitate, the process that occurs is peptization, resulting in the formation of a colloidal sol.

### Final Answer:
The process through which the colloidal sol is formed is known as **peptization**.

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