One mole of methane undergoes complete combustion in a stoichiometric amount of air. The reaction proceeds as CH4 + 2O2 → CO2 + 2H2O. Both the reactants and products are in gas phase. ΔH°298 = - 730 kJ/mole of methane. Mole fraction of water vapour in the product gases is about

• 0.19
• 0.33
• 0.40
• 0.67