CBSE Class 12-science Answered

 In the case of Na₂S₄O₆, if we observe the structure of this compound it is found that there are two types of sulphur atoms

1)     O.S. of first sulphur: sulphur is attached to the same sulphur atoms hence there is no change in the electronic arrangement of this sulphur atom, therefore, its O.S. is zero.

2)     O.S. of second sulphur: This atom of sulphur is attached to the three oxygen atoms two are doubly bonded and one is singly bonded

Therefore for doubly bonded oxygen will exert the charge +2 and for singly bonded oxygen will +1. hence on total, the O.S. of Second sulphur is +5.