Aerosol is a system of colloidal particles having a size of

Options

A. `5mum`
B. `1-2 mum`
C. less than `100 mum`
D. more than `10 mum`

Answer

**Step-by-Step Solution:**

1. **Understanding Aerosols**: Aerosols are systems that consist of colloidal particles. These particles can be either solid or liquid and are suspended in air or another gas.

2. **Particle Size of Aerosols**: The size of aerosol particles is crucial for their classification. Aerosols typically consist of fine particles or droplets.

3. **Options Analysis**: The question provides four options for the size of aerosol particles:
- 5 micrometers
- 1 to 2 micrometers
- Less than 100 micrometers
- More than 10 micrometers

4. **Determining the Correct Size**:
- Aerosols are generally characterized by having particles that are very small, typically less than 1 micrometer in diameter.
- While the options include sizes larger than this, the defining characteristic of aerosols is that they consist of very fine particles.

5. **Conclusion**: Based on the understanding of aerosols and their particle size, the correct answer is that aerosols have a size of **less than 1 micrometer**.

**Final Answer**: Less than 1 micrometer.

---