What is the oxidation number for s in the compound so3? (recall that o has an oxidation number of –2.) 0 +2 +4 +6

The compound So3 is neutral. This means that the total charge on the compound is zero.

Now SO3 has 1 S and 3 O.
Recalling that O has an oxidation number of -2, this means that the 3 O in SO3 would have a total oxidation number of 3*-2 = -6

Now, as mentioned before, the total charge of SO3 is zero. This means that the total positive charge is equal to the total negative charge.

Total charge of SO3 = charge on S + charge on O3
0 = charge on S - 6
Charge on S = +6

The answer is d. +6
(i got it right on my quiz)