A radioactive sample consists of two distinct species having equal number of atoms $N_0$ initially. The mean-life of one species is $\tau $ and of the other is $5\tau $. The decay products in both cases is stable. The total number of radioactive nuclei at $t = 5\tau $ is
${N_0}\left( {\frac{{{e^5} + 1}}{{{e^5}}}} \right)$
${N_0}\left( {\frac{{{e^4} + 1}}{{{e^5}}}} \right)$
${N_0}\left( {\frac{{e + {e^5}}}{{{e^5}}}} \right)$
$N_0e^{-3}$
In a sample of radioactive material, what percentage of the initial number of active nuclei will decay during one mean life .......... $\%$
The activity of a sample is $64 × 10^{-5}\, Ci.$ Its half-life is $3\, days$. The activity will become $5 × 10^{-6}\, Ci$ after .........$days$
The activity of a radioactive sample is measured as $N_0$ counts per minute at $t = 0$ and $N_0/e$ counts per minute at $t = 5\, minutes$. The time (in $minutes$) at which the activity reduces to half its value is
Write the law of radioactive decay.
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 .........$hours$