Question

In which of the following species does the sulfur atom have the lowest oxidation number?

a. HS−
b. SO2
c. SO3

Answer 1

a

Step-by-step explanation:

a. H usually has oxidation number of +1. if this was a neutral molecule, then S would have an oxidation number of -1, but since the molecule has a charge -1, and such oxidation number doesn't exist for S in first place, then S has an oxidation number of -2.

b. O usually has an oxidation number of -2. there are 2 oxygen atoms, they total -4. this is a neutral molecule so oxidation number of S must be +4, which is one of its possible numbers as well

c. there are 3 oxygen atoms, they total -6. this is a neutral molecule so oxidation number of S must be +6, and this is one of its possible numbers as well