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 ..........$years$
$11460$
$17190$
$22920$
$45840$
The half life of a radioactive substance is $20$ minutes. In $........\,minutes$ time,the activity of substance drops to $\left(\frac{1}{16}\right)^{ th }$ of its initial value.
A radioactive nucleus ${ }_{\mathrm{Z}}^{\mathrm{A}} \mathrm{X}$ undergoes spontaneous decay in the sequence
${ }_{\mathrm{Z}}^{\mathrm{A}} \mathrm{X} \rightarrow {}_{\mathrm{Z}-1}{\mathrm{B}} \rightarrow {}_{\mathrm{Z}-3 }\mathrm{C} \rightarrow {}_{\mathrm{Z}-2} \mathrm{D}$, where $\mathrm{Z}$ is the atomic number of element $X.$ The possible decay particles in the sequence are :
The decay constants of a radioactive substance for $\alpha $ and $\beta $ emission are ${\lambda _\alpha }$ and ${\lambda _\beta }$ respectively. If the substance emits $\alpha $ and $\beta $ simultaneously, then the average half life of the material will be
$N$ atoms of a radioactive element emit $n$ number of $\alpha$-particles per second. Mean life of the element in seconds, is
The sample of a radioactive substance has $10^6$ nuclei. Its half life is $20 \,s$. The number of nuclei that will be left after $10 \,s$ is nearly ...... $\times 10^5$