Which process involves the combination of both oxidation and reduction?

The process that involves both oxidation and reduction is known as redox, which is short for reduction-oxidation. In a redox reaction, one substance loses electrons (oxidation) while another gains electrons (reduction). This interplay is fundamental to many chemical processes, especially in biological systems and energy production.

For instance, in cellular respiration, glucose undergoes oxidation and the oxygen is reduced, illustrating the redox process in action. The term "redox" explicitly captures this duality of electron transfer, making it essential for understanding various reactions in chemistry.

The other processes listed, such as decomposition, synthesis, and neutralization, do not involve this fundamental transfer of electrons in the same paired manner. Decomposition refers to the breaking down of a compound, synthesis involves the combination of substances to form a new compound, and neutralization is a reaction between an acid and a base that results in the formation of water and a salt, typically without involving direct electron transfer as characterized in redox reactions. Therefore, recognizing redox as the process where both oxidation and reduction occur highlights its importance in chemistry.