WAEC Chemistry 2020 Paper

Concept:A reducing agent is a substance that donates electrons and is oxidised in a redox reaction.An oxidising agent gains electrons and is reduced.Explanation:Carbon ($\mathrm{C}$), carbon monoxide ($\mathrm{CO}$), and hydrogen ($\mathrm{H}_2$) are common reducing agents.They readily give electrons to other substances during chemical reactions.Oxygen ($\mathrm{O}_2$) readily accepts electrons, so it acts as a strong oxidising agent.Therefore, among the given options, oxygen is not a reducing agent.Answer:C. $\mathrm{O}_2$