The ratio activity of an element becomes $\frac{{1}}{{64}} th$ of its original value in $60\, sec$. Then the half life period is ............$sec$
$5$
$10$
$20$
$30$
Activity of a radioactive substance is $R_1$ at time $t_1$ and $R_2$ at time $t_2(t_2 > t_1).$ Then the ratio $\frac{R_2}{R_1}$ is :
A certain radioactive nuclide of mass number $m_x$ disintegrates, with the emission of an electron and $\gamma$ radiation only, to give second nuclied of mass number $m_y.$ Which one of the following equation correctly relates $m_x$ and $m_y$ ?
What fraction of a radioactive material will get disintegrated in a period of two half-lives
Curie is a unit of
A radioactive sample decays by $\beta$ -emission. In first two seconds $‘n’$ $\beta$ -particles are emitted and in next $2\ seconds$ , $‘0.25n’$ $\beta$ -particles are emitted. The half life of radioactive nuclei is ...... $sec$