For the consecutive unimolecular-type first-order reaction A→k1R→k2S, the concentration of component R, CR at any time t is given by -CR=CA0K1[e−k1t(k2−k1)+e−k2t(k1−k2)]if CA=CA0,CR=CR0=0 at t=0The time at which the maximum concentration of R occurs is -