JEE Advanced 2022 · Paper 1 · Chemistry Q10

ChemistryMultiple correct+4 / -2Question 46 of 54

The correct option(s) related to adsorption processes is(are)

Chemisorption results in a unimolecular layer.

The enthalpy change during physisorption is in the range of 100 to 140 kJ mol

^{-1}

Chemisorption is an endothermic process.

Lowering the temperature favors physisorption processes.

Answer and worked solution

Official answer: A, D

(A) True. Chemisorption involves chemical bonds to surface sites, so it stops at a monolayer.

(B) False. The enthalpy of physisorption is only about 20-40 kJ mol⁻¹; values of 80-240 kJ mol⁻¹ are typical of chemisorption.

(C) False. Chemisorption is exothermic.

(D) True. Physisorption is exothermic and has no activation barrier, so lower temperature favours it.

JEE Advanced 2022 · Paper 1, Chemistry question 10