In an oxidation-reduction (redox) reaction, which molecule is reduced?

• A. The molecule that loses electrons
• B. The molecule that increases its oxidation number
• C. The molecule that gains electrons
• D. The molecule that acts as the oxidizing agent

Answer: (C)

Verified step by step guidance

1. Understand the definition of reduction in a redox reaction: reduction is the gain of electrons by a molecule, atom, or ion.
2. Recall that oxidation is the loss of electrons, which corresponds to an increase in oxidation number.
3. Identify that the molecule that gains electrons undergoes reduction and its oxidation number decreases.
4. Recognize that the molecule that loses electrons is oxidized and acts as the reducing agent.
5. Note that the molecule that causes another to be oxidized (by accepting electrons) is called the oxidizing agent and itself is reduced.