If $T$ is the half life of a radioactive material, then the fraction that would remain after a time $\frac{T}{2}$ is
$\frac{1}{2}$
$\frac{3}{4}$
$\frac{1}{{\sqrt 2 }}$
$\frac{{\sqrt 2 - 1}}{{\sqrt 2 }}$
A radio isotope has a half life of $75\, years$. The fraction of the atoms of this material that would decay in $150\, years$ will be...........$\%$
The half life period of a radioactive substance is 60 days. The time taken for $\frac{7}{8}$ th of its original mass to disintegrate will be $......days$
The radioactivity of a certain radioactive element drops to $1/64$ of its initial value in $30\, seconds$. Its half life is .........$seconds$
Half life of a radio-active substance is $20\, minutes$. The time between $20\%$ and $80\%$ decay will be ........... $minutes$
A freshly prepared radioactive sample of half- life $1$ hour emits radiations that are $128$ times as intense as the permissible safe limit. The minimum time after which this sample can be safely used is .........$hours$