The property of colloid is

Options

A. Scattering of light
B. setting under gravity
C. Dialysis
D. Emulsion

Answer

To solve the question regarding the properties of colloids, we will analyze each option provided and determine which one correctly describes a property of colloids.

### Step-by-Step Solution:

1. **Understanding Colloids**:
- Colloids are mixtures where tiny particles are dispersed throughout another substance. These particles are larger than molecules but smaller than those in a suspension.

2. **Analyzing the Options**:
- **Option A: Scattering of Light**:
- This is a well-known property of colloids. When light passes through a colloidal solution, it is scattered by the colloidal particles, which is known as the Tyndall effect. This effect is a definitive characteristic of colloidal systems.

- **Option B: Setting Under Gravity**:
- Colloidal particles do not settle under gravity due to their small size and the Brownian motion that keeps them suspended. Therefore, this is not a property of colloids.

- **Option C: Dialysis**:
- Dialysis is a process used to separate small solute particles from colloidal particles and is not a property of colloids themselves. It is a purification technique.

- **Option D: Emulsion**:
- An emulsion is a specific type of colloid where liquid droplets are dispersed in another liquid. While it is related to colloids, it is not a property of colloids in general.

3. **Conclusion**:
- Based on the analysis, the correct answer is **Option A: Scattering of Light**, as it is a fundamental property of colloids demonstrated by the Tyndall effect.

### Final Answer:
The property of colloid is **scattering of light** (Option A).