Which one of the following does not represent a colloidal system?

Options

A. Smoke
B. Ink
C. Air
D. Blood

Answer

To determine which of the following does not represent a colloidal system, we need to understand the characteristics of a colloid. A colloidal system consists of two main components: a dispersed phase and a dispersion medium. The dispersed phase is present in a smaller quantity, while the dispersion medium is present in a larger quantity.

### Step-by-Step Solution:

1. **Understanding Colloidal Systems**:
- A colloid is a heterogeneous mixture where the particle size of the dispersed phase is larger than that in a solution but smaller than that in a suspension.

2. **Identifying Components**:
- The dispersed phase is the substance that is dispersed (e.g., solid particles), and the dispersion medium is the substance in which the dispersed phase is distributed (e.g., liquid or gas).

3. **Analyzing Options**:
- **Option 1: Smoke** - This is a colloid where solid particles are dispersed in air (gas).
- **Option 2: Ink** - This is also a colloid where solid particles are dispersed in a liquid (water).
- **Option 3: Air** - Air is a homogeneous mixture of gases and does not have a dispersed phase; hence, it does not represent a colloidal system.
- **Option 4: Blood** - Blood is a colloid where solid components (cells) are dispersed in a liquid (plasma).

4. **Conclusion**:
- Among the options, air does not represent a colloidal system because it lacks a dispersed phase and is a homogeneous mixture.

Thus, the correct answer is **Option 3: Air**.