State the law of radioactive decay.

Plot a graph showing the number (N) of undecayed nuclei as a function of time (f) for a given radioactive sample having half life $\quad { T }*{ 1/2 }.$
Depict in the plot, the number of undecayed nuclei at
(i) t = ${ 3T }*{ 1/2 }$ and

(ii) t = ${ 5T }_{ 1/2 }$