The diffusion of particles in colloid is 

Options

A. rapid than in true solution
B. slower than in suspension
C. slower than in true solution
D. equal as in true solution

Answer

To solve the question regarding the diffusion of particles in a colloid, we will analyze the properties of colloidal solutions, true solutions, and suspensions, focusing on the size of the particles and their mobility.

### Step-by-Step Solution:

1. **Understanding Particle Sizes**:
- True solutions contain solute particles that are smaller than 1 millimicron (1 nm).
- Colloidal solutions have particle sizes ranging from 1 millimicron to 1 micron.
- Suspensions contain larger particles, typically greater than 1 micron.

2. **Definition of Diffusion**:
- Diffusion is the process where solute particles move from an area of higher concentration to an area of lower concentration when two solutions are in direct contact.

3. **Comparing Diffusion Rates**:
- The rate of diffusion depends on the size of the particles and their mobility.
- Since true solution particles are smaller than colloidal particles, they can move more freely and rapidly compared to colloidal particles.

4. **Analyzing the Options**:
- **Faster than true solution**: This cannot be true as true solution particles are smaller and diffuse faster.
- **Slower than suspension**: This is incorrect because colloidal particles are smaller than those in a suspension, allowing for faster movement compared to suspensions.
- **Slower than true solution**: This is correct because colloidal particles are larger than true solution particles, resulting in slower diffusion.
- **Equal to true solution**: This is also incorrect since the particle sizes differ.

5. **Conclusion**:
- The correct answer is that the diffusion of particles in a colloid is slower than in a true solution.

### Final Answer:
The diffusion of particles in a colloid is slower than in a true solution.