# 10 mole of $SO_2$ and 15 mole of $O_2$ were passed over catalyst to produce 8 mole of $SO_3$.The ratio of $SO_2$ and $SO_3$ moles in mixture is
$\begin{array}{1 1}(a)\;\large\frac{5}{4}&(b)\;\large\frac{1}{4}\\(c)\;\large\frac{1}{2}&(d)\;\large\frac{3}{4}\end{array}$