Which of the following statements is not correct for chemisorption and physisorption ?

Options

A. 1. Physical adsorption occurs at a low temperature and chemisorption occurs at all temperature
B. 2.Magnitude of chemisorption decreases with rise in temperature while physisorption increases with rise in temperature .
C. 3. Chemisorption is irreversible and physisorption is reversible .
D. 4. In physisorption, activation energy is low while in chemisorption, it is high.

Explanation

To determine which statement is not correct regarding chemisorption and physisorption, we need to analyze each statement provided in the question.

### Step-by-Step Solution:

1. **Understanding Physisorption and Chemisorption**:
- **Physisorption**: This is the adsorption process that occurs due to weak van der Waals forces. It typically occurs at low temperatures and is reversible.
- **Chemisorption**: This involves the formation of strong chemical bonds (covalent or ionic) between the adsorbate and the surface. It can occur at various temperatures but is generally irreversible.

2. **Analyzing the Statements**:
- **Statement 1**: "Physical adsorption occurs at low temperature and chemisorption occurs at all temperatures."
- This statement is generally correct because physisorption is favored at low temperatures, while chemisorption can occur at a range of temperatures.

- **Statement 2**: "Magnitude of chemisorption decreases with rise in temperature while physisorption increases with rise in temperature."
- This statement is incorrect. Chemisorption typically increases with temperature initially (up to a certain point) due to increased kinetic energy, and then may decrease. Physisorption, on the other hand, generally decreases with an increase in temperature as the adsorbed molecules gain enough energy to overcome the weak forces holding them to the surface.

- **Statement 3**: "Chemisorption is irreversible and physisorption is reversible."
- This statement is correct. Chemisorption involves strong bonds that are not easily broken, making it irreversible, while physisorption is reversible due to weak van der Waals forces.

- **Statement 4**: "In physisorption, activation energy is low while in chemisorption it is high."
- This statement is also correct. Physisorption requires little to no activation energy, while chemisorption requires a higher activation energy to form chemical bonds.

3. **Conclusion**:
- The statement that is not correct is **Statement 2**: "Magnitude of chemisorption decreases with rise in temperature while physisorption increases with rise in temperature."

### Final Answer:
The incorrect statement is: "Magnitude of chemisorption decreases with rise in temperature while physisorption increases with rise in temperature."