Which class includes benzaldehyde, eugenol, and vanillin?

Which class includes benzaldehyde, eugenol, and vanillin?

• A. Aldehydes
• B. Esters
• C. Terpenes
• D. Aromatics

Answer: (D)

All three molecules feature a benzene ring, which is the defining feature of aromatic compounds. Benzaldehyde and vanillin are aromatic aldehydes, and eugenol is a phenylpropene with a benzene ring—none of them rely on a single functional group to define them. The unifying thread is the aromatic ring, not a specific functional group. The other options describe groups or classes that don’t apply to all three: aldehydes miss eugenol; esters would require an ester linkage present in none of them; terpenes are a broad class based on isoprene units and don’t capture all three. So, aromatic compounds is the best fit.

All three molecules feature a benzene ring, which is the defining feature of aromatic compounds. Benzaldehyde and vanillin are aromatic aldehydes, and eugenol is a phenylpropene with a benzene ring—none of them rely on a single functional group to define them. The unifying thread is the aromatic ring, not a specific functional group. The other options describe groups or classes that don’t apply to all three: aldehydes miss eugenol; esters would require an ester linkage present in none of them; terpenes are a broad class based on isoprene units and don’t capture all three. So, aromatic compounds is the best fit.