A hydrocarbon is defined as?

• A. Molecules contain only hydrogen and carbon atoms covalently bonded
• B. Molecules containing hydrogen, carbon, plus oxygen
• C. Molecules containing carbon, hydrogen, and nitrogen
• D. Molecules containing only carbon

Answer: (A)

Hydrocarbons are molecules made only from carbon and hydrogen, connected by covalent bonds. This means the substance contains no other elements like oxygen or nitrogen. That exact description matches the idea that the molecule has only hydrogen and carbon atoms covalently bonded. If a molecule includes oxygen or nitrogen, it isn’t a hydrocarbon, and a molecule made only of carbon isn’t a hydrocarbon because it lacks hydrogen.