Which one of the following characteristics is associated with adsorption?
(a) G, H and S all are negative
(b) G and H are negative but S is positive
(c) G and S are negative but H is positive
(d) G is negative but H and S are positive
(a) Adsorption is a spontaneous process that occurs with release in energy and decrease. In the randomness (i.e. entropy) of the adsorbed substance.
For a spontaneous process, G must be negative.
G = H - TS
As the process is exothermic and randomness of molecule (entropy) decreases hence, both H and S will be negative as well.