What is the oxidation number of sulfur (S) in magnesium sulfate (MgSO4) ?

A. + 2

B. + 3

C. + 6 <--?

D. + 7

Mg: it has a fixed oxidation number 2 + in any compound

O: it has an oxidation number 2-, except in peroxides.

The oxidation number of S is such that the net charge of the compound, Mg SO4 is zero.

Call x the oxidation number of S:

(2+) + (x) + 4 (2-) = 0 = > x = + 8 - 2 = + 6

Answer: Option C. + 6