Which term best fits the definition: in chemical reactions, the loss of electrons by one reactant?

• A. Reduction
• B. Redox
• C. Oxidizing agent
• D. Oxidation

Answer: (D)

The key idea is that oxidation is the process of losing electrons. When a reactant loses electrons, its oxidation state increases, so that substance is oxidized. In a redox reaction, this loss of electrons by one partner is paired with another partner gaining those electrons (reduction). The term redox describes the overall coupled process, not the act of losing electrons by itself. An oxidizing agent is the species that accepts electrons and is reduced, enabling the other reactant to be oxidized. Reduction, by contrast, is the gain of electrons, the opposite process. So the term that best fits the given definition is oxidation.