Solution :
We have given ,
a number of moles of hydrogen and $n_{H})$ that oxygen are $(n_0)$ not equal
$\therefore $ We have , the relation between radio number moles escaped and ratio of molecular mass.
$\large\frac{n0_2}{nH_2}=\sqrt{\large\frac{Mh_2}{Mo_2}}$
M= Molecular mass of the molecules
$\large\frac{n0_2}{nH_2}=\sqrt{\large\frac{2}{32}}$
$\large\frac{n0_2}{nH_2}=\sqrt{\large\frac{1}{16}}$
$\large\frac{n0_2}{0.5}=\sqrt{\large\frac{1}{4}}$
$no_2=\large\frac{0.5}{4}=\frac{1}{8}$