(a) Sulphur has greater tendency for catenation than oxygen. Give reasons.
or Oxygen shows catenation behaviour less than sulphur.
(b) Sulphur exhibits greater tendency for calenation than selenium. Give reasons.

Explanation

(a) Due to smaller size of oxygen than sulphur, the lone pairs of electrons on the oxygen atoms repel the bond pair of the O-O bond to a greater extent than the lone pairs of electrons on the sulphur atoms repel the bond pair of S-S bond. As a result, S-S bond is much stronger (213 kJ `mol^(-1)`) than O-O bond (138 kJ `mol^(-1)`) and hence sulphur has a much greater tendency for catenation than oxygen.
(b) As we move from S to Se, the atomic size increases and hence the strength of Element-Element bond decreases. Thus, S-S bond is much stronger than Se-Se bond and consequently, S shows greater tendency for catenation than selenium.