ABC Class 1 Physical/Chemical Operator Practice Exam

The process where reactants are transformed into products through breaking and forming chemical bonds is called a chemical reaction. In a chemical reaction, the original substances undergo a change at the molecular level, resulting in the creation of new substances with different properties. This transformation involves the rearrangement of atoms, with bonds being broken in the reactants and new bonds being formed in the products.

Understanding that chemical reactions involve not just changes in state but also the formation of entirely new compounds helps differentiate them from processes like diffusion or physical changes. For instance, diffusion describes the movement of particles from an area of higher concentration to an area of lower concentration, without any alteration to their molecular structure. On the other hand, a physical change involves changes that do not affect the intrinsic chemical identities of the substances, such as changes in state (solid, liquid, gas) or form (breaking a solid into smaller pieces).

Catalysis refers to the facilitation of a chemical reaction by a substance called a catalyst, which speeds up the reaction without being consumed in the process but does not define the transformation of reactants into products itself. Thus, the definition provided perfectly aligns with the concept of a chemical reaction, making it the correct choice.