$A$ radioactive isotope decays at such a rate that after $96 \ min$,only $\frac{1}{8}$ of the original amount remains. The half-life of this nuclide in minutes is:

$A$ radioactive substance takes $20 \, \text{min}$ to decay $25 \%$. How many minutes will it take to decay $75 \%$?

During a nuclear explosion,one of the products is $^{90}Sr$ with a half-life of $28.1 \ years$. If $1 \ \mu g$ of $^{90}Sr$ was absorbed in the bones of a newly born baby instead of calcium,how much of it will remain after $10 \ years$ and $60 \ years$ if it is not lost metabolically?

If a substance with a half-life of $3 \ days$ is kept for $12 \ days$,what fraction of the substance remains?

The half-life period $t_{1/2}$ of a radioactive element is $N$ years. The period of its complete decay is

The number of $\alpha$-particles emitted per second by a radioactive element falls to $1/32$ of its original value in $50 \ days$. The half-life period of this element is .......... $days$.