The half-life of $10 \ g$ of a radioactive substance is $10 \ days$. The half-life of $20 \ g$ of the same substance is .......... $days$.

$A$ radioactive isotope having $t_{1/2} = 3 \ days$ was measured after $12 \ days$. If $3 \ g$ of the isotope remains in the container,what was the initial weight of the isotope (in $g$)?

$A$ substance of which $1 \ g$ is taken,after one half-life period,what fraction of it is left?

If $8.0 \ g$ of a radioactive substance has a half-life of $10 \ hrs.$,the half-life of $2.0 \ g$ of the same substance is .......... $hr$.

If the amount of radioactive substance is increased three times,the number of atoms disintegrated per unit time would

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