The half-life period of a radioactive element is $140$ days. After $560$ days,one gram of the element will reduce to

$A$ certain nuclide has a half-life period of $30 \ minutes$. If a sample containing $600$ atoms is allowed to decay for $90 \ minutes$,how many atoms will remain?

The half-life of the radio element $_{83}Bi^{210}$ is $5 \ days$. Starting with $20 \ g$ of this isotope,the amount remaining after $15 \ days$ is ......... $g$. (in $g$)

$A$ certain nuclide has a half-life of $25 \ min$. If one starts with $100 \ g$ of it,how much of it will remain at the end of $100 \ min$?

$1.0 \, g$ of a radioactive isotope was found to reduce to $125 \, mg$ after $24 \, hours$. The half-life of the isotope is $....... \, hours$.

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