The radioactivity of a sample is $R_1$ at time $T_1$ and $R_2$ at time $T_2.$ If the half life of the specimen is $T.$ Number of atoms that have disintegrated in time $(T_2 - T_1)$ is proportional to
$(R_1T_1 - R_2T_2)$
$(R_1 - R_2) T$
$(R_1 - R_2)/T$
$(R_1 - R_2) (T_1 - T_2)$
If the decay or disintegration constant of a radioactive substance is $\beta $, then its half life and mean life are respectively
$(log_e \,2 =ln\, 2)$
$1\, Curie $ is equal to
Two species of radioactive atoms are mixed in equal number. The disintegration constant of the first species is $\lambda$ and of the second is $\lambda / 3$. After a long time the mixture will behave as a species with mean life of approximately
Half lives for $\alpha$ and $\beta$ emission of a radioactive material are $16$ years and $48$ years respectively. When material decays giving $\alpha$ and $\beta$ emission simultaneously then time in which $\frac{3}{4}$ th of the material decays is ....... years
The mean life of a radioactive sample are $30\,year$ and $60\,year$ for $\alpha -$ emission and $\beta -$ emission respectively. If the sample decays both by $\alpha -$ emission and $\beta -$ emission simultaneously, then the time after which, only one-fourth of the sample remain is approximately ............ $years$