$10\, gm$ of radioactive material of half-life $15$ year is kept in store for $20$ years. The disintegrated material is ............$gm$
$12.5 $
$10.5$
$6.04$
$4.03 $
Write the law of radioactive decay.
At $t = 0$, number of active nuclei in a sample is $N_0$. How much no. of nuclei will decay in time between its first mean life and second half life?
$99 \%$ of a radioactive element will decay between
The count rate of a Geiger- Muller counter for the radiation of a radioactive material of half life of $30\, minutes$ decreases to $5\,{s^{ - 1}}$ after $2\, hours.$ The initial count rate was..........${s^{ - 1}}$
Activity of a radioactive substance can be represented by various unit. Select correct option