Which gas is a product of combustion reactions?

Combustion reactions are chemical processes where a substance reacts with oxygen, usually producing heat and light. The primary products of combustion depend on the nature of the fuel being burned. In complete combustion, especially of hydrocarbons, carbon and hydrogen in the fuel react with oxygen to yield carbon dioxide and water.

Carbon dioxide is a significant product of this reaction, especially when natural fossil fuels like gasoline or methane are combusted. During this process, the carbon present in the fuel oxidizes, leading to the production of carbon dioxide gas as a byproduct. This is why carbon dioxide is recognized as a key product of combustion reactions, particularly in scenarios where fuels are burned in sufficient oxygen, allowing for complete oxidation.

The other gases listed—oxygen, nitrogen, and helium—are not products of the combustion process. While oxygen is a reactant, nitrogen is typically inert under combustion conditions and does not participate directly in the reaction. Helium is a noble gas and does not engage in combustion at all, making carbon dioxide the only correct answer in this context. Through this understanding, it becomes clear why carbon dioxide is identified as a product arising from combustion reactions.