Q. Two radioactive elements $X$ and $Y$ have half-life times of $50$ minutes and $100$ minutes, respectively. Samples $X$ and $Y$ initially contain equal numbers of atoms. After $200$ minutes, the ratio
$\frac{\text { number of undecayed atoms of } X}{\text { number of undecayed atoms of } Y}$ is.

Solution:

After $200$ minutes the number of $X$ will reduce to $1/ 16$ and that of $Y$ will reduce to $1/4$.

Questions from Nuclei