Question

What is the oxidation number of S in H2SO3?

Answer 1

`+4`

Explanation:

We start of by giving the oxidation number for hydrogen and oxygen, since we know these already.
So we have 2 hydrogen which each has a charge of `+1`, and we have 3 oxygen which each has a charge of `-2`. If we cancel these out we would have that sulfur should have a charge of `+4` to give a total charge of `0`.