If $'f^{\prime}$ denotes the ratio of the number of nuclei decayed $\left(N_{d}\right)$ to the number of nuclei at $t=0$ $\left({N}_{0}\right)$ then for a collection of radioactive nuclei, the rate of change of $'f'$ with respect to time is given as:
$[\lambda$ is the radioactive decay constant]
$\lambda\left(1-{e}^{-\lambda t}\right)$
$-\lambda e^{-\lambda t}$
$\lambda e^{-\lambda t}$
$-\lambda\left(1-{e}^{-\lambda . t}\right)$
In a mean life of a radioactive sample
Give the different units of radioactivity and define them.
Two radioactive materials $A$ and $B$ have decay constant $5\lambda$ and $\lambda$ respectively.At $t=0$ they have the same number of nuclei, then the ratio of the number of nuclei of $A$ to that $B$ will be $(1/e)^2$ after a time interval
The half life of a radioactive element which has only $\frac{1}{{32}}$ of its original mass left after a lapse of $60\, days$ is ........$days$
Activity of a radioactive substance can be represented by various unit. Select correct option