Assertion :- During physical adsorption multimolecular layers are formed.
Reason :- For physical adsorption value of `Delta H=-20` to -40 kJ/mol.

Options

A. If both Assertion & Reason are True & the Reason is a correct explanation of the Assertion.
B. If both Assertion & Reason are True but Reason is not a correct explanation of the Assertion.
C. If Assertion is True but the Reason is False.
D. If both Assertion & Reason are False.

Answer

To solve the question, we need to analyze both the assertion and the reason provided.

### Step 1: Understand the Assertion
The assertion states that "During physical adsorption, multimolecular layers are formed."

- **Explanation**: Physical adsorption, also known as physisorption, occurs when adsorbate molecules adhere to the surface of an adsorbent through weak van der Waals forces. Because these forces are weak, multiple layers of adsorbate can form on the surface of the adsorbent. Hence, the assertion is true.

### Step 2: Understand the Reason
The reason states that "For physical adsorption, the value of ΔH is -20 to -40 kJ/mol."

- **Explanation**: The change in enthalpy (ΔH) for physical adsorption is indeed negative, typically in the range of -20 to -40 kJ/mol. This indicates that the process is exothermic, meaning that energy is released when the adsorbate adheres to the adsorbent. Therefore, this reason is also true.

### Step 3: Analyze the Relationship between Assertion and Reason
Now we need to determine if the reason correctly explains the assertion.

- **Analysis**: While both the assertion and the reason are true, the reason does not provide a correct explanation for why multimolecular layers are formed during physical adsorption. The formation of these layers is due to the weak van der Waals forces, not directly due to the enthalpy change.

### Conclusion
Both the assertion and the reason are true, but the reason does not correctly explain the assertion. Therefore, the correct answer is:

**Option V**: Both assertion and reason are true, but the reason is not the correct explanation of the assertion.

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