State reasons for each of the following :
(i) All the P-Cl bonds in `PCl_5` molecule are not equivalent.
(ii) Sulphur has greater tendency for catenation than oxygen.

Explanation

(i) The three equatorial P-Cl bonds are equivalent, while the two axial bonds are longer than equatorial bonds. This is due to the fact that the axial bond pairs suffer more repulsion as corn pared to equatorial bond pairs.
(ii) Catenation is the tendency of an atom to form bonds with identical atoms. In this group, only sulphur has a tendency for catenation. Due to small size, the long pairs of e-s on the oxrgen atoms repel the bond pair of O-O bond to a greater extend than that the long pairs of e-s on the sulphur atom in S-S bond. As a result, S-S bond is much stronger than · O-O bond. Hence S has a tendency for catenation than c.