Which is not lyophilic colloid ?

Options

A. milk
B. gum
C. fog
D. blood

Answer

To determine which of the following options is not a lyophilic colloid, we first need to understand what lyophilic colloids are.

### Step-by-Step Solution:

1. **Definition of Lyophilic Colloids**:
- Lyophilic colloids are also known as "liquid-loving" colloids. They have a strong affinity for the solvent (usually water) in which they are dispersed. This means that when they are mixed with a suitable liquid, there is a high force of attraction between the colloid particles and the liquid.

2. **Characteristics of Lyophilic Colloids**:
- They are stable and do not easily separate from the solvent.
- They can be easily dispersed in the solvent and can form stable colloidal solutions.
- Examples include substances like starch, gelatin, and gum.

3. **Identifying the Options**:
- We need to look at the options provided in the question to identify which one does not fit the criteria of a lyophilic colloid.
- Common examples of colloids include blood, milk, fog, and gum.

4. **Analysis of Each Option**:
- **Blood**: Although blood is a colloidal system, it behaves more like a lyophobic colloid due to its complex composition and the presence of cells and proteins.
- **Milk**: Milk is a classic example of a lyophilic colloid, as it is stable and has a strong affinity for water.
- **Fog**: Fog is an example of a lyophobic colloid, as it consists of tiny water droplets suspended in air and does not have a strong affinity for the liquid.
- **Gum**: Gum is also a lyophilic colloid, as it dissolves well in water and forms a stable solution.

5. **Conclusion**:
- Based on the analysis, the option that is not a lyophilic colloid is **Fog**.

### Final Answer:
Fog is not a lyophilic colloid.