Final answer:
When a chemical is reduced, it gains electrons and this results in a reduction of its potential energy, which aligns with answer (a). Reduction is part of redox reactions, essential to understanding energy transfer, especially within biological systems.
Step-by-step explanation:
When a chemical is reduced during a reaction, it experiences the gain of electrons. This gain of electrons typically corresponds to a decrease in oxidation state and as such, a reduction in potential energy. Therefore, the correct answer is (a) It gains electrons and loses potential energy.
Oxidation-reduction reactions, or redox reactions, involve a transfer of electrons where the substance losing electrons is oxidized, and the substance gaining electrons is reduced. This is an essential concept in both chemistry and biochemistry because it underlies energy transfer within cells. An easy mnemonic to remember this concept is 'OIL RIG', which stands for Oxidation Is Loss of an electron and Reduction Is Gain of an electron.
In summary, during a reduction chemical reaction, the compound gains electrons, which effectively reduces its potential energy. An analogy often used to explain this concept is that of rocks rolling downhill, releasing potential energy in the process—similar to how a reduced chemical compound 'gives up' energy when it gains electrons.