During the combustion of methane (CH4), one mole of methane gas combines with two moles of oxygen gas (O2) to produce one mole of carbon dioxide gas (CO2) and two moles of water vapor. Which of the following chemical equations correctly represents the combustion of methane described above?
a)CH4(g) + 2O(g) ↔ CO2(g) + 2H2O(g)
b)CH4(g) + 2O(g) ↔ CO(g) + 2H2O(l)
c)CH4(g) + 2O2(g) ↔ CO2(g) + 2H2O(g)
d)CH4(g) + 2O2(g) ↔ CO(g) + 2H2O(l)