Airborne bacteria and viruses form a colloidal system of __ in __. The blanks can be correctly filled by:

Options

A. Solid, Gas
B. Gas, solid
C. Solid, solid
D. Solid, liquid

Answer

To solve the question "Airborne bacteria and viruses form a colloidal system of __ in __," we need to identify the correct components of the colloidal system.

### Step-by-Step Solution:

1. **Understanding Colloidal Systems**:
- A colloidal system consists of two phases: the dispersed phase and the dispersion medium. The dispersed phase is the substance that is present in a smaller amount, while the dispersion medium is the substance that is present in a larger amount.

2. **Identifying the Phases**:
- In the case of airborne bacteria and viruses, these are microscopic entities that are suspended in the air. Here, the bacteria and viruses represent the dispersed phase, while the air acts as the dispersion medium.

3. **Determining the Type of Colloid**:
- Since bacteria and viruses are solid particles dispersed in a gaseous medium (air), this forms a specific type of colloidal system. The classification of colloids includes solid in gas, liquid in gas, gas in liquid, etc.

4. **Filling in the Blanks**:
- Based on the analysis, we can conclude that airborne bacteria and viruses form a colloidal system of **solid** (the bacteria and viruses) in **gas** (the air).

5. **Final Answer**:
- Therefore, the correct way to fill in the blanks is: "Airborne bacteria and viruses form a colloidal system of **solid** in **gas**."