If the half-life of an element is $69.3 \text{ hours}$,what percentage of it will decay between the $10^{\text{th}}$ and $11^{\text{th}}$ hours? (Initial activity $= 50 \mu Ci$)

The half-life of a radioactive isotope $X$ is $20$ years. It decays to another element $Y$,which is stable. The two elements $X$ and $Y$ were found to be in the ratio $1:7$ in a sample of a given rock. The age of the rock is estimated to be:

The half-life period of a radioactive element $X$ is the same as the mean life time of another radioactive element $Y$. Initially,both of them have the same number of atoms. Then:

The half-life of a radioactive element is $12.5 \; h$ and its initial quantity is $256 \; g$. After how much time (in $h$) will its quantity remain $1 \; g$?

The graph shows $\ln \left| \frac{dN(t)}{dt} \right|$ versus $t$ for a radioactive sample. If the number of radioactive nuclei decreases by a factor of $p$ after $4.16$ years,then $p = $.....

Substance $A$ has an atomic mass number of $16$ and a half-life of $1$ day. Another substance $B$ has an atomic mass number of $32$ and a half-life of $0.5$ day. If both $A$ and $B$ start undergoing radioactivity simultaneously with an initial mass of $320 \, g$ each,how many total atoms of $A$ and $B$ combined would be left after $2$ days? (Answer in $......... \times 10^{24}$)