Which compound is a product of complete combustion?

Complete combustion of a hydrocarbon occurs when there is enough oxygen available for the reaction to fully convert the fuel into carbon dioxide and water. In this process, carbon in the fuel binds with oxygen from the air to form carbon dioxide, which is a greenhouse gas and is emitted as a primary product of complete combustion.

To elaborate, when a hydrocarbon (like methane) undergoes complete combustion in the presence of sufficient oxygen, it reacts to produce carbon dioxide and water as the main products. Therefore, carbon dioxide is the key indicator of complete combustion. This process is fundamental in understanding energy production in engines and heating systems, where efficiency and the complete conversion of fuel into usable energy are critical.

The other compounds listed are not products of complete combustion. For instance, carbon monoxide is produced during incomplete combustion, which occurs when there isn't enough oxygen available, leading to partial oxidation and the formation of this harmful gas. Oxygen is a reactant, not a product, while methane itself is a hydrocarbon fuel rather than a product of combustion.