The rate constant of the reaction A ->B is 0.6 × 10–3 mol L-1 second-1. If the concentration of A is 5 M then concentration of B after 20 minutes is: (NEET 2015 RS)

Rate constant k = 0.6 × 10–3 mol L-1 second-1. (unit mol L-1 second-1 shows zero order reaction) For a zero order reaction [A] = [A]0 – kt and [A0] – [A] = [B] = kt = 0.6 × 10–3 × 20 × 60 = 0.72 M