Element M burns in excess oxygen to yield a solid whose empirical formula is M2O2. When this solid is carefully acidified with dilute sulfuric acid, O2 gas is evolved. Assume that the oxygen atoms in the solid have identical oxidation states.
(a) Determine the oxidation state of oxygen in M2O2 and explain how the laboratory observation supports your answer.
(b) Deduce the ionic charge on element M in this compound.
(c) Predict the empirical formula of the simplest chloride that element M would form and justify your prediction through charge balance.
(d) The solid product is sometimes described as a "peroxide." Explain what distinguishes a peroxide ion from an oxide ion, both in terms of electron count and typical reactivity.