The half-life period of a radioactive substance is $8 \ years$. After $16 \ years$,the mass of the substance will reduce from starting $16.0 \ g$ to ....... $g$.

If $87.5\%$ of a given substance disintegrates in $40 \text{ minutes}$,what is the half-life of the radioactive substance?

The decay constant of a radioactive element is $3 \times 10^{-6} \ min^{-1}$. Its half-life is

Radioactive lead $_{82}Pb^{201}$ has a half-life of $8 \ hours$. Starting from $1 \ mg$ of this isotope,how much will remain after $24 \ hours$?

The ratio of the amount of two elements $X$ and $Y$ at radioactive equilibrium is $1 : 2 \times 10^{-6}$. If the half-life period of element $Y$ is $4.9 \times 10^{-4} \ days$,then the half-life period of element $X$ will be .......... $days$.

The half-life of a radioactive element is $100 \, \text{min}$. The time interval between the stages of $50\%$ and $87.5\%$ decay will be ...... $\text{min}$.