Certain radioactive substance reduces to $25\%$ of its value in $16\ days$. Its half-life is .......... $days$

The half-life of a radioactive substance is $T$. The time taken, for disintegrating $\frac{7}{8}$ th part of its original mass will be

The half life of radium is $1620$ years and its atomic weight is $226\, k\,gm$ per kilomol. The number of atoms that will decay from its $1\, gm$ sample per second will be

(Avogadro's number $N = 6.02 \times {10^{26}}$atom/kilomol)

Half-lives of two radioactive elements $A$ and $B$ are $20$ minutes and $40$ minutes, respectively. Initially, the samples have equal number of nuclei. After $80$ minutes, the ratio of decayed number of $A$ and $B$ nuclei will be

Half life of a radioactive substance is $T$. The time taken for all the nuclei to disintegrate will be

The graph between the instantaneous concentration $(N)$ of a radioactive element and time $(t)$ is