The half-life of radium is $1580 \ yrs$. Its average life will be:

$A$ 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 $g$)?

$A$ 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 $100 \ min$?

If $3/4$ of a radioactive element disintegrates in $2$ hours,its half-life would be

The radioactivity of a radioactive element becomes $\frac{1}{10}$ of the original radioactivity after $2.303 \ s$. The half-life period is: (in $s$)

Given that a radioactive species decays according to the exponential law $N = N_0 e^{-\lambda t}$,the half-life of the species is: