Why do physisorption and chemisorption behave differently with rise in temperature ?

Explanation

Phaysisorption is due to weak van der Walls forces. Thetse weaken with rise in temperature. Hence, physisorption decreases. Chemisorption involves formation of chemical bond which requires activation energy like any other chemical reaction. Rise in temperature provides the required activation energy and hence initially it increases with increase of temperature and then decreases due to exothermic nature of adsorption equlibrium.