At some instant, a radioactive sample $S_1$ having an activity $5\,\mu Ci$ has twice the number of nuclei as another sample $S_2$ which has an activity of $10\,\mu Ci.$ The halflives of $S_1$ and $S_2$ are
$10$ years and $20$ years, respectively
$5$ years and $20$ years, respectively
$20$ years and $10$ years, respectively
$20$ years and $5$ years, respectively
Half life of radium is $1620$ years. How many radium nuclei decay in $5$ hours in $5\, gm$ radium? ( Atomic weight of radium $= 223$)
The fossil bone has a ${}^{14}C:{}^{12}C$ ratio, which is $\left[ {\frac{1}{{16}}} \right]$ of that in a living animal bone. If the halflife of ${}^{14}C$ is $5730\, years$, then the age of the fossil bone is ..........$years$
The radioactivity of a certain radioactive element drops to $1/64$ of its initial value in $30\, seconds$. Its half life is .........$seconds$
Define the average life of a radioactive sample and obtain its relation to decay constant and half life.
The activity of a sample reduces from $A_0$ to ${A_0} / \sqrt{3}$ in one hour. The activity after $3$ hours more will be