If there is a limited supply of oxygen during combustion of hydrocarbons what is produced?

• A. Carbon dioxide
• B. Carbon monoxide
• C. Water
• D. Salt

Answer: (B)

When oxygen is limited, combustion is incomplete, so the carbon in the hydrocarbon is only partially oxidized. This produces carbon monoxide, a gas formed when carbon atoms gain just enough oxygen to form CO rather than the fully oxidized carbon dioxide. Water can still form from hydrogen, but the defining outcome of restricted oxygen is CO formation rather than CO2. Carbon dioxide requires ample oxygen for complete oxidation, and salt is not a product of hydrocarbon combustion.