Which of the following is the best description of a chemical reaction? a. when molecules of a substance move slowly enough, they link together to form a crystalline structure. b. when two molecules collide with enough force, old chemical bonds are broken and new bonds form, resulting in one or more new substances. c. when two molecules collide with enough force, they shatter into individual atoms. later, these atoms join up in new combinations to form new substances. d. when two atoms collide with enough force, their nuclei fuse together, forming new substances and releasing tremendous amounts of energy.