The reaction in which the reactant forms an intermediate and the intermediate forms the product in one or many subsequent reactions recalled consecutive reactions.
Ak1→Bk2→C
A= reactant, B intermediate, C = product only the reactant A will be present As the reaction starts, A produces an intermediate B through K1, rate constant As and when B is formed, it produces the product C through K1, rate constant. After the completion of reaction only is present and concentrations of A and B will be zero.