Question

oxygen exist as O2 and sulphure exist as S8

Answer 1

Answer:

because to complete octet & form stable molecule

but in case s8 it is crown structure to form stable molecule

Answer 2

Answer:

o has absent d orbital it means it have less unpaired electrons than s

so for becoming stable o needs 2e- for following the nearest Nobel gas configuration and thus s needs 8e- for following nearest Nobel gas configuration