Which of the following is a product of burning hydrocarbons?

Burning hydrocarbons primarily produces energy, carbon dioxide, and water as significant byproducts, but incomplete combustion can also generate carbon monoxide. When hydrocarbons combust in a limited oxygen supply, the carbon atoms do not fully oxidize to carbon dioxide, leading to the formation of carbon monoxide. This gas is toxic and can be particularly harmful when inhaled.

In contrast, oxygen is a reactant in the combustion process rather than a product. Nitrogen, while often present in the atmosphere and involved in many reactions, is not a product of hydrocarbon combustion. Hydrogen can be released during some chemical reactions involving hydrocarbons, but it does not directly result from the combustion process itself. Therefore, carbon monoxide is the most relevant byproduct in this context, especially under conditions of incomplete combustion.