General form for rate law for aA → products

• A. rate = k[A]^m[B]^n
• B. rate = k[A]^m
• C. rate = k
• D. rate = k/[A]^m

Answer: (B)

Rate laws tell you how the speed of a reaction depends on the concentrations of its reactants. For a reaction with a single reactant A turning into products, the rate can depend on A raised to some power. The general form is rate = k[A]^m, where m is the order with respect to A and is determined experimentally. The rate constant k encodes temperature effects and details of the mechanism. This form covers all possibilities for a single reactant: if m happens to be zero, you get rate = k (a zero-order case), and if m is one, you have rate = k[A], and so on. The other patterns would imply involvement of another reactant or an inverse dependence, which don’t match the simple single‑reactant rate law.