In a sample of radioactive material, what percentage of the initial number of active nuclei will decay during one mean life .......... $\%$
$69.3$
$63$
$50$
$37$
A radioactive substance emits
The half-life of a radioactive nuclide is $100 \,hours.$ The fraction of original activity that will remain after $150\, hours$ would 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)
Tritium has a half-life of $12.5\; y$ undergoing beta decay. What fraction of a sample of pure tritium will remain undecayed after $25\; y.$
The half-life of $^{215}At$ is $100\mu s$. The time taken for the radioactivity of a sample of $^{215}At$ to decay to $\frac{{1}}{{16}} \,th$ of its initial value is .........$\mu s$