Half lives for $\alpha$ and $\beta$ emission of a radioactive material are $16$ years and $48$ years respectively. When material decays giving $\alpha$ and $\beta$ emission simultaneously then time in which $\frac{3}{4}$ th of the material decays is ....... years
$29$
$24$
$64$
$12$
For a certain radioactive process the graph between $In\, {R}$ and ${t}\,({sec})$ is obtained as shown in the figure. Then the value of half life for the unknown radioactive material is approximately $....\,{sec}.$
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...........$\%$
Certain radio-active substance reduces to $25\%$ of its value in $16$ days. Its half-life is ........ $days$
In a radioactive material, fraction of active material remaining after time $t$ is $\frac{9}{16}$ The fraction that was remaining after $\frac{t}{2}$ is
Carbon dating is best suited for determining the age of fossils if their age in years is of the order of