Determine the rate constant for each of the following second-order reactions:

(a) 2 A → B + 2 C, given that the concentration of A decreases from 2.50 mmol · L^–1 to 1.25 mmol · L^–1 in 100 s;

(b) A → C + 2 D, given that [A]₀ = 0.300 mol · L^–1 and that the concentration of C increases to 0.010 mol · L^–1 in 200. s. In each case, express your results in terms of the rate law for the loss of A.