What are the products of complete combustion of methane?

• A. Carbon monoxide and water
• B. Carbon dioxide and water
• C. Carbon dioxide and oxygen
• D. Carbon monoxide and oxygen

Answer: (B)

When a methane molecule burns in plenty of oxygen, it is fully oxidized, producing carbon dioxide and water. The balanced equation is CH4 + 2 O2 → CO2 + 2 H2O. This shows that all the carbon ends up as CO2 and all the hydrogen ends up as H2O, with no leftover oxygen and no other products. If oxygen were limited, you could get incomplete combustion with carbon monoxide or carbon (soot), but that wouldn’t be complete combustion. Among the options, carbon dioxide and water are the actual products of complete combustion for methane.