Question

Which one of the following is not the correct characteristic property of physical adsorption?

• A. It is not specific in nature
• B. Enthalpy of adsorption of this is low
• C. It increases with increase of temperature
• D. It is a multilayer adsorption under high pressure

Hint:

Physical adsorption is exothermic, and thus, it decreases with increase in temperature. Always apply Le Chatelier's principle to adsorption phenomena.

Answer 1

The Correct Option is C

Step 1: Understand physical adsorption characteristics. - Physical adsorption is non-specific in nature. 
- Enthalpy of adsorption is low (typically 20–40 kJ/mol). 
- It forms multilayers especially under high pressure. 
- However, it decreases with increase in temperature, since it is an exothermic process (Le Chatelier’s principle). 
Step 2: Identify the incorrect statement. Option (3) says physical adsorption increases with temperature, which contradicts the above point. Hence, it is the incorrect statement.