Which is not a colloidal solution ?

Options

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

Answer

To determine which option is not a colloidal solution, we need to understand what a colloidal solution is and how it differs from other types of mixtures.

### Step-by-Step Solution:

1. **Definition of Colloidal Solution**: A colloidal solution consists of two phases: the dispersed phase (dp) and the dispersion medium (dm). The dispersed phase contains small particles that are not visible to the naked eye and remain suspended in the dispersion medium.

2. **Characteristics of Colloidal Solutions**: Colloidal solutions are heterogeneous mixtures, meaning that the components can be distinguished from one another. The dispersed particles do not settle out over time and cannot be separated by filtration.

3. **Examples of Colloidal Solutions**:
- **Smoke**: This is an aerosol where the dispersed phase is solid (soot) and the dispersion medium is gas (air).
- **Ink**: This is a colloidal solution where the dispersed phase is solid (pigment) and the dispersion medium is liquid (water).
- **Blood**: This is also a colloidal solution where the dispersed phase includes cells and the dispersion medium is plasma (liquid).

4. **Identifying Non-Colloidal Solutions**: To find out which option is not a colloidal solution, we need to consider mixtures that are homogeneous rather than heterogeneous.

5. **Air**: Air is a mixture of gases (like nitrogen, oxygen, carbon dioxide) that are uniformly mixed. It does not have a dispersed phase that can be distinguished from the dispersion medium, making it a homogeneous mixture.

6. **Conclusion**: Among the options provided, air is not a colloidal solution because it is a homogeneous mixture of gases.

### Final Answer:
**Air is not a colloidal solution.**

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