Chemical Equilibrium

One mole each of He and $\mathrm{A}(\mathrm{g})$ are taken in a 10 L closed flask and heated to 400 K to establish the following equilibrium.

\(\mathrm{A}(\mathrm{~g}) \rightleftharpoons \mathrm{B}(\mathrm{~g})\)

$\mathrm{K}_{\mathrm{c}}$ for this reaction at 400 K is 4.0 . The partial pressures (in atm) of He and B(g) are respectively (at equilibrium)

(Assume $\mathrm{He}, \mathrm{A}(\mathrm{g})$ and $\mathrm{B}(\mathrm{g})$ behave as ideal gases)

(Given : $\mathrm{R}=0.082 \mathrm{~L} \mathrm{~atm} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}$ )