A 10 g mixture of hydrogen and helium is contained in a vessel of capacity $0.0125 \mathrm{~m}^3$ at 6 bar and $27^{\circ} \mathrm{C}$. The mass of helium in the mixture is $\_\_\_\_$ g. (nearest integer) Given : $\mathrm{R}=8.3 \mathrm{JK}^{-1} \mathrm{~mol}^{-1}$ (Atomic masses of H and He are 1 u and 4 u , respectively)