Rate of physical adsorption increases with

Which one of the following is an incorrect statement for physisorption?

The substance used to decolourise and purify oils is

Why is chemisorption referred to as activated adsorption?

The force of attraction present in physical adsorption is ....

Amongst the following statements regarding adsorption,those that are valid are :
$(a)$ $\Delta H$ becomes less negative as adsorption proceeds.
$(b)$ On a given adsorbent,ammonia is adsorbed more than nitrogen gas.
$(c)$ On adsorption,the residual force acting along the surface of the adsorbent increases.
$(d)$ With increase in temperature,the equilibrium concentration of adsorbate increases.