$^{14}C$ has a half-life of $5760 \ years$. $100 \ mg$ of a sample containing $^{14}C$ is reduced to $25 \ mg$ in ......... $years$.

The $t_{1/2}$ of a radioactive element is $20 \ min$. The time interval between the stages of its $33\%$ and $67\%$ decay is ....... $min$.

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

After $2 \, \text{hours}$,the amount of a certain radioactive substance reduces to $1/16^{th}$ of the original amount (the decay process follows first-order kinetics). The half-life of the radioactive substance is $...... \, \text{min}$.

$A$ 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:

In the case of a radioisotope,the value of $T_{1/2}$ and $\lambda$ are identical in magnitude. The value is