Testing MultipleChoice Question 3

A solid $\mathrm{XY}$kept in an evacuated sealed container undergoes decomposition to form a mixture of gases $\mathrm{X} \mathrm{and} \mathrm{Y}$ at temperature $\mathrm{T}$.

The equilibrium pressure is $10 \mathrm{bar}$ in this vessel. ${\mathrm{K}}_{\mathrm{p}}$ for this reaction is?

Expression for ${\mathrm{K}}_{\mathrm{p}}$ for the reaction $3\mathrm{Fe}\left(\mathrm{s}\right)+4{\mathrm{H}}_2\mathrm{O}\left(\mathrm{g}\right)\rightleftharpoons {\mathrm{Fe}}_3{\mathrm{O}}_4\left(\mathrm{s}\right)+4{\mathrm{H}}_2\left(\mathrm{g}\right)$ can be written as $\mathrm{Kp}=$_____.

(A) $\frac{{\mathrm{p}}_{{\mathrm{H}}_2}}{{\mathrm{p}}_{{\mathrm{H}}_2\mathrm{O}}}$
(B) $\frac{{\mathrm{p}}_{{\mathrm{H}}_2\mathrm{O}}}{{\mathrm{p}}_{{\mathrm{H}}_2}}$
(C) $\frac{{\left({\mathrm{p}}_{{\mathrm{H}}_2}\right)}^4}{{\left({\mathrm{p}}_{{\mathrm{H}}_2\mathrm{O}}\right)}^4}$
(D) $\frac{{\left({\mathrm{p}}_{{\mathrm{H}}_2\mathrm{O}}\right)}^4}{{\left({\mathrm{p}}_{{\mathrm{H}}_2}\right)}^4}$

Enter your correct answer as A, B, C or D. $$