K L M
(i) Electronic configuration of sulphur (S): 2, 8, 6
Electronic configuration of Oxygen (O): 2, 6
(ii) Sulphur and oxygen, both needs 2 electron to complete its octet. Thus valency of both Sulphur and Oxygen is 2.
(iii) Isotopes are variants of same element with same atomic number but different atomic mass. Hence they are not isotopes.