Collidal solution is a heterogeneous solution which contains particle of intermediate size, i.e., (diameter between 1 and 1000 nm) colloidal is not a substance but it is a state of a substance which depends upon the molecular size. Colloidal solutions are intermediate between ture solution and suspensions.
Chemisorption

Options

A. Increases with temperature
B. Decreases with temperature
C. Remains unaffected by change of temperature.
D. First increases and then decreases.

Answer

To solve the question regarding the behavior of chemisorption with temperature, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Chemisorption**:
- Chemisorption is a type of adsorption where a chemical bond is formed between the adsorbate and the surface of the adsorbent. It typically has a high activation energy compared to physisorption.

2. **Effect of Temperature on Chemisorption**:
- As temperature increases, the kinetic energy of the molecules also increases. This can lead to an increase in the rate of chemisorption initially because more molecules have enough energy to overcome the activation energy barrier.

3. **Initial Increase in Chemisorption**:
- At lower temperatures, as the temperature rises, the rate of chemisorption increases due to the increased kinetic energy of the molecules. This means that more molecules can successfully collide with the surface and form bonds.

4. **Reaching a Peak**:
- There comes a point where the increase in temperature continues to provide energy, but the system reaches a saturation point where the surface is fully occupied, and the adsorption sites are limited.

5. **Decrease in Chemisorption**:
- After reaching this peak, further increases in temperature can lead to a decrease in chemisorption. This is because the excess energy can cause the adsorbed molecules to desorb from the surface, breaking the chemical bonds formed during chemisorption.

6. **Conclusion**:
- Therefore, the overall trend for chemisorption with temperature is that it first increases and then decreases. This behavior can be represented graphically, showing an initial rise followed by a decline.

7. **Final Answer**:
- The correct option regarding the behavior of chemisorption with temperature is that it "first increases and then decreases."