There are two radioactive substances A and B. Decay constant of B is two times that of A. Initially, both have equal number of nuclei. After n half-lives of A, rates of disintegration of both are equal. The value of n is
let . Initially the rate of disintergration of A is and that of B is . After one half life of A, rate of disintegration will become ( half life of B = one half the half life of A). n=1