Final answer:
In the rate expression for the reaction between zinc and hydrochloric acid, the concentration of zinc is not included because zinc is a solid, and its reaction rate depends on surface area rather than concentration. The correct option is B.
Step-by-step explanation:
In determining the rate expression for the reaction between zinc and hydrochloric acid, the concentration of zinc is not used in the rate law because Zinc is a solid. In kinetics, the rate of a reaction involving solids is typically independent of the amount of solid because the reaction rate is surface area dependent, not concentration dependent.
Solids have a fixed surface area contact with the other reactants and this doesn't change with the amount of solid. That's why the rate law for these types of reactions typically includes only the concentrations of aqueous or gaseous reactants, which for this reaction would primarily be the concentration of hydrochloric acid (HCl).