• # question_answer ${{H}_{2}}{{O}_{2}}$ changes to ${{O}_{2}}$. What is the change in oxidation number of oxygen per atom?

${{\overset{+1}{\mathop{H}}\,}_{2}}{{\overset{-1}{\mathop{O}}\,}_{2}}\xrightarrow{\,}{{\overset{0}{\mathop{O}}\,}_{2}}$ Change in O.N. of oxygen per atom = 1 unit.