A freshly prepared sample of a radioisotope of half-life $1386 \ s$ has activity $10^3$ disintegrations per second. Given that In $2=0.693$, the fraction of the initial number of nuclei (expressed in nearest integer percentage) that will decay in the first $80 \ s$ after preparation of the sample is :
$4$
$5$
$6$
$7$
A radioactive reaction is $_{92}{U^{238}}{ \to _{82}}P{b^{206}}$. How many $\alpha $ and $\beta $ particles are emitted
Carbon dating is best suited for determining the age of fossils if their age in years is of the order of
Write the definition and unit of decay constant.
$'Rn$' decays into $'Po'$ by emitting $a -$ particle with half life of $4\, days$. A sample contains $6.4 \times 10^{10}$ atoms of $Rn$. After $12\, days$, the number of atoms of $'Rn'$ left in the sample will be
$\beta$- rays emitted by a radioactive material are