What is the oxidation state of S in #S_2O_3^-2#?
We can see that the net charge of the molecule is
To start of we find the oxidation state of oxygen, in the molecule.
Oxygen has a oxidation state of
Formally we gots
We got the thiosulfate ion
Since oxygen is more electronegative than sulfur, then oxygen will have its usual
So, the sum of the oxidation numbers of the sulfur atoms is