The correct statement(s) pertaining to the adsorption of a gas on a solid surface is(are)
(i) adsorption is always exothermic
(ii) physisorption may transform into chemsisorption transform into chemisorption at high temperature
(iii) physisorption increases with increasing temperature but chemisorption decreases with increasing temperature .
(iv) chemisorption is more exothermic than physisorption , however it is very slow due to higher energy of activation.
A. (i) and (iv) only
B. (ii) and (iii) only
C. (i),(ii) and (iv) only
D. All of these.