Question

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

विकल्प

• 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 favours physisorption processes.

Answer 1

Chemisorption results in a unimolecular layer.

Lowering the temperature favours physisorption processes.

Explanation:

Chemisorption results in a unimolecular (monolayer) layer because once gas molecules form strong chemical bonds with the surface, further layers cannot be formed.

Lowering the temperature favours physisorption since it is an exothermic process with low activation energy and weak van der Waals forces, which are stronger at lower temperatures.

The enthalpy change during physisorption is about 20 to 40 kJ mol⁻¹, not 100 to 140 kJ mol⁻¹.

Chemisorption is an exothermic process, not endothermic.