Calculate the oxidation number of sulphur

CHEMISTRY · Subjective · A Level · Chemistry · Oxidation, reduction and redox reactions · Oxidation, reduction and redox reactions

Problem

Calculate the oxidation number of sulphur, chromium and nitrogen in

\text{H}_2\text{SO}_5

\text{Cr}_2\text{O}_7^{2-}

and

\text{NO}_3^-

. Suggest structure of these compounds. Count for the fallacy.