Certain radio-active substance reduces to $25\%$ of its value in $16$ days. Its half-life is ........ $days$
$32$
$8$
$64$
$28$
Samples of two radioactive nuclides, $X$ and $Y$, each have equal activity $A_0$ at time $t = 0$ . $X$ has a half life of $24$ years and $Y$ a half life of $16$ years. The samples are mixed together.What will be the total activity of the mixture at $t = 48$ years ?
A radioactive reaction is $_{92}{U^{238}}{ \to _{82}}P{b^{206}}$. How many $\alpha $ and $\beta $ particles are emitted
Define the disintegration rate or radioactivity of a sample and obtain the relation $R = \lambda N$ and define its different units.
Tritium has a half-life of $12.5\; y$ undergoing beta decay. What fraction of a sample of pure tritium will remain undecayed after $25\; y.$
Define $SI$ unit of radioactivity ?