`._(84)Po^(218) (t_(1//2) = 3.05 min)` decays to `._(82)Pb^(214) (t_(1//2) = 2.68 min)` by `alpha` emisison while `Pb^(214)` is `beta`-emitter. In an experiment starting with `1 g` atom of pure `Po^(218)`, how much time would be required for the concentration of `Pb^(214)` to reach maximum?