Determine the rate constant for each of the following first-order reactions, in each case expressed for the rate of loss of A:

(a) A → B, given that the concentration of A decreases to one-half its initial value in 1000. s; 

(b) A → B, given that the concentration of A decreases from 0.67 mol · L^–1 to 0.53 mol · L^–1 in 25 s; 

(c) 2 A → B + C, given that [A]₀ = 0.153 mol · L^–1 and that after 115 s the concentration of B rises to 0.034 mol · L^–1.