What describes a redox reaction?

A redox reaction is characterized by the simultaneous occurrence of oxidation and reduction processes. In these reactions, one substance loses electrons (oxidation) while another gains electrons (reduction), which is what defines the term "redox," derived from the combination of "reduction" and "oxidation." This transfer of electrons is essential for various chemical processes, including energy production in biological systems and numerous industrial applications.

In the context of the other options, the first choice suggests that redox reactions are exclusive to metals, which is not accurate, as non-metals can also participate in redox reactions. The second choice implies that reduction can happen without oxidation, which contradicts the fundamental principle of redox reactions that they always occur together. The last option states there is no transfer of electrons, which directly contradicts what defines a redox process, as it fundamentally relies on the exchange of electrons between reactants. Therefore, the definition of a redox reaction aligns precisely with the understanding that both oxidation and reduction occur concurrently.