In an experiment 50 ml of 0.1 (M) solution of a salt is reacted with 25 ml of 0.1 (M) solution of sodium sulphite. The half equation for the oxidation of sulphite ion is

${\mathrm{SO}}_3^{2-}\left(\mathrm{aq}\right) + {\mathrm{H}}_2\mathrm{O}\left(\mathrm{l}\right) \stackrel{ }{\to } {\mathrm{SO}}_4^{2-} \left(\mathrm{aq}\right) + 2{\mathrm{H}}^{+}\left(\mathrm{aq}\right) + 2{\mathrm{e}}^{-}$

If the oxidation number of metal in the salt was 3, what would be the new oxidation number of metal ?