Methane, CH4\text{CH}_4CH4, is used as a fuel in a boiler. During complete combustion, one molecule of methane forms one molecule of CO2\text{CO}_2CO2 and two molecules of H2O\text{H}_2\text{O}H2O. The possible numbers of O2\text{O}_2O2 molecules needed are 1, 2, 3 or 4.
How many molecules of oxygen react with one molecule of methane?
2
1
4
3