Total pressure of a mixture of \[{{H}_{2}}\] and \[{{O}_{2}}\] is 1.00 bar. The mixture is allowed to react to form water, which is completely removed to leave only pure \[{{H}_{2}}\] at a pressure of 0.35 bar. Assuming ideal gas behaviour and that all pressure measurements were made under the same temperature and volume conditions, the composition of the original mixture is

• A. \[{{X}_{{{H}_{2}}}}\]\[{{X}_{{{O}_{2}}}}\]0.500.50
• B. \[{{X}_{{{H}_{2}}}}\]\[{{X}_{{{O}_{2}}}}\]0.220.78 
• C. \[{{X}_{{{H}_{2}}}}\]\[{{X}_{{{O}_{2}}}}\]0.780.22
• D. \[{{X}_{{{H}_{2}}}}\]\[{{X}_{{{O}_{2}}}}\]0.350.65