All colloidal dispersions have

Options

A. very high osmotic pressure
B. Low osmotic pressure
C. No osmotic pressure
D. High osmotic pressure

Explanation

To answer the question "All colloidal dispersions have," we can analyze the properties of colloidal dispersions, particularly focusing on osmotic pressure.

### Step-by-Step Solution:

1. **Understanding Colloidal Dispersions**:
- Colloidal dispersions consist of tiny particles (colloids) dispersed in a continuous medium (liquid, gas, or solid). These particles are larger than molecules but smaller than what can be seen with the naked eye.

2. **Osmotic Pressure**:
- Osmotic pressure is a colligative property, which means it depends on the number of solute particles in a solution rather than the nature of those particles.

3. **Colligative Properties**:
- Colligative properties include vapor pressure lowering, boiling point elevation, freezing point depression, and osmotic pressure. These properties depend on the concentration of solute particles.

4. **Nature of Colloidal Particles**:
- In colloidal dispersions, the particles are aggregates of molecules. Due to their size and the way they interact with the solvent, they do not contribute significantly to osmotic pressure compared to true solutions.

5. **Conclusion**:
- As a result, all colloidal dispersions exhibit low osmotic pressure. This is because the large size of colloidal particles means that they do not exert the same osmotic pressure as smaller solute particles in a true solution.

### Final Answer:
All colloidal dispersions have low osmotic pressure.