Final answer:
The rate law for the given elementary reactions are provided.
Step-by-step explanation:
For elementary reactions, the rate law can be directly written based on the reaction stoichiometry. Here are the rate laws for the given reactions:
For reaction a (2A + B → products), the rate law is rate = k[A]^2[B].
For reaction b (A + 2B → products), the rate law is rate = k[A][B]^2.
For reaction c (3C → products), this is a termolecular reaction, so the rate law is rate = k[C]^3.
For reaction d (D → products), as a unimolecular reaction, the rate law is rate = k[D].
The orders of the reactions are determined by the number of molecules involved in the reaction (molecularity), hence the exponent in the rate law corresponds to the number of molecules of each reactant.