Heat And Thermodynamics

A vessel of volume $27 \times 10^4 \mathrm{cc}$, contains a mixture of Hydrogen (molar mass $=2 \mathrm{~g} \mathrm{~mol}^{-1}$ ) and oxygen (molar mass $=32 \mathrm{~g} \mathrm{~mol}^{-1}$ ) gas at standard temperature and pressure. If the mass of hydrogen is 16 g , find the mass of oxygen gas contained in the vessel.