Final answer:
The gain of electrons or a decrease in oxidation state during a chemical reaction is called reduction, not oxidation or a redox reaction. Oxidation involves the loss of electrons, whereas reduction is the gain of electrons. Both occur simultaneously in a redox reaction. The correct option is 1).
Step-by-step explanation:
The gain of electrons or a decrease in oxidation state of a molecule, atom, or ion is called reduction. Therefore, the correct answer to the question is 1) reduction. To further understand this concept, oxidation and reduction are parts of a broader set of reactions known as redox reactions.
Oxidation is characterized by the loss of electrons, gain of oxygen, or loss of hydrogen. Conversely, reduction is defined as the gain of electrons, the loss of oxygen, or the gain of hydrogen. These processes are intimately connected; when one substance is oxidized, another is reduced simultaneously. Option 1) is the correct one.
Examples:
- Oxidation: Fe0 → Fe2+ + 2e- (Iron is oxidized by losing electrons)
- Reduction: O2 + 4e- → 2O2- (Oxygen is reduced by gaining electrons)