The ratio of molecular mass of two radioactive substances is 3/2 and the ratio of their decay constants is 4/3 . then, the ratio of their intial activity per mole will be

Activity, A=−dNdt=λN . As the number of nuclei (N) per mole are equal for both the substances, irrespective of their molecular mass, therefore, A∝λ .A1A2=λ1λ2=43 .