An example of colloidal sol in which the affinity of the sol particles for the medium is due to hydrogen bonding is

Options

A. Sulphur in water
B. Gold in water
C. `Fe(OH)_(3)` in water
D. Protein in water

Explanation

To solve the question regarding an example of a colloidal sol where the affinity of the sol particles for the medium is due to hydrogen bonding, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Colloidal Sols**:
- A colloidal sol consists of two phases: the dispersed phase (particles) and the dispersion medium (liquid or gas). The interaction between these phases is crucial in determining the properties of the colloid.

2. **Identify Types of Colloids**:
- Colloids can be classified into two main types: lyophilic (solvent-attracting) and lyophobic (solvent-repelling). Lyophilic colloids have a strong affinity for the dispersion medium.

3. **Focus on Hydrogen Bonding**:
- Hydrogen bonding is a specific type of attractive interaction that occurs between molecules, particularly when a hydrogen atom is bonded to a highly electronegative atom (like oxygen or nitrogen).

4. **Consider Examples of Lyophilic Colloids**:
- In the context of lyophilic colloids, proteins are a significant example. They can form colloidal solutions in water due to their polar nature and ability to form hydrogen bonds with water molecules.

5. **Conclude with the Example**:
- Therefore, the example of a colloidal sol in which the affinity of the sol particles for the medium is due to hydrogen bonding is **protein in water**. This is because the protein molecules interact strongly with water through hydrogen bonds, leading to a stable colloidal solution.

### Final Answer:
The example of a colloidal sol in which the affinity of the sol particles for the medium is due to hydrogen bonding is **protein in water**.