Question

Which one of the following is true?

• A. Both physisorption and chemisorption depend on the nature of the gas
• B. Physisorption is irreversible
• C. Chemisorption is not specific in nature
• D. Enthalpy of adsorption is high in physisorption
• E. Chemisorption increases with surface area of adsorbent while in physisorption it is not

Answer 1

The Correct Option is A

Which one of the following is true?

• Chemisorption is not specific in nature
• Physisorption is irreversible
• Both physisorption and chemisorption depend on the nature of the gas
• Enthalpy of adsorption is high in physisorption
• Chemisorption increases with surface area of adsorbent while in physisorption it is not

Correct Answer: Both physisorption and chemisorption depend on the nature of the gas

Explanation:

• Physisorption involves weak van der Waals forces and is influenced by the polarisability of the gas.
• Chemisorption depends on the ability of the gas to form a chemical bond with the surface, so it is also gas-specific.

Incorrect Statements:

• Chemisorption is specific because it involves chemical bond formation.
• Physisorption is usually reversible, not irreversible.
• Physisorption has low enthalpy change (~20–40 kJ/mol), while chemisorption has high enthalpy (~80–200 kJ/mol).
• Both types of adsorption increase with surface area of adsorbent.