In a radioactive sample there are $1.414 \times 10^6$ active nuclei. If they reduce to $10^6$ within $10\, minute$ then the half life of this sample will be ....... $min$
$5$
$20$
$15$
$30$
For a substance the average life for $\alpha$-emission is $1620$ years and for $\beta$ emission is $405$ years. After how much time the $1/4$ of the material remains after $\alpha$ and $\beta$ emission .......$years$
The half-life of a radioactive substance is $30$ minutes. The times (in minutes ) taken between $40\%$ decay and $85\%$ decay of the same radioactive substance is
The half-life of radon is $3.8\, days$. Three forth of a radon sample decay in ............$days$
A sample which has half life of $10^{33}$ year, if initial number of nuclei of the sample is $26 \times 10^{24}$. Then the number of nuclei decayed in $1$ year is ........... $ \times 10^{-7}$
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 .........$\mu s$