Reactants are converted to products by what process?

The conversion of reactants to products in a chemical reaction primarily involves the process of breaking and forming bonds. In a reaction, the bonds within the reactant molecules are disrupted due to the energy input, allowing atoms to rearrange and form new bonds to create the product molecules. This bond-breaking and bond-making process is fundamental to all chemical reactions, whether they are simple combinations of elements or complex biochemical reactions in living organisms.

While oxidation-reduction reactions specifically involve the transfer of electrons and can result in the conversion of substances, they represent a subset of reactions that also entail breaking and forming bonds. Facilitated diffusion and exocytosis are processes associated with the movement of substances across cell membranes rather than reactions that convert reactants into products. Thus, the general process of breaking and forming bonds encompasses all types of chemical transformations, making it the most accurate answer to the question.