Why a zero order reaction can not be a single step reaction? Please explain.
A Zero-order reaction has a rate which is independent of the concentration of the reactant(s). Increasing the concentration of the reacting species will not speed up the rate of the reaction. Zero-order reactions are typically found when a material required for the reaction to proceed, such as a surface or a catalyst is saturated by the reactants. That’s why it is impossible for zero order reaction be a single step reaction. All processes with catalyst take place to form intermediate, so you have two steps at least.