A solid $XY$ kept in an evacuated sealed container undergoes decomposition to form a mixture of gases $X$ and $Y$ at temperature $T$. The equilibrium pressure is $10\; bar$ in this vessel. $K_p$ for this reaction is :

Question

$\begin{array}{1 1}(1) 5 \\(2) 10\\ (3) 25\\ (4) 100 \end{array}$