• # question_answer The ratio of molecular masses of two radioactive substances is 3/2 and the ratio of their decay constants is 4/3, Then, the ratio of their initial activities per mole will be A)  2                                             B)  4/3 C)  8/9                        D)         9/8

Activity,$A=\frac{-dN}{dt}=\lambda N$ As the number of nucleic (N) per mole are equal for both the substances, irrespective of their molecular mass therefore, $A\propto \lambda$ $\frac{{{A}_{1}}}{{{A}_{2}}}=\frac{{{\lambda }_{1}}}{{{\lambda }_{2}}}=\frac{4}{3}$