WAEC Chemistry 2014 Paper

Concept:Reduction is classically defined as the loss of oxygen from a substance.Explanation:In the reaction $\mathrm{CuO} + \mathrm{H}_2 \rightarrow \mathrm{Cu} + \mathrm{H}_2\mathrm{O}$, copper(II) oxide loses oxygen to form copper metal. Therefore, $\mathrm{CuO}$ is reduced. Loss of electrons and loss of hydrogen are definitions of oxidation, not reduction. Addition of electronegative elements also describes oxidation. Hence, reduction is the loss of oxygen.Answer:C. loss of oxygen