Oxidation Number of 'S' in H2SO4 ?

In  $H2SO4$,

Hydrogen has a charge of +2, with each hydrogen has +1.

Oxygen has  a charge of -8, with each oxugen has -2.

Total charge = (2 - 8) = -6

Therefore, the Oxidation number of Sulphur S is '+6' because to make the compound stable.