Which statement best defines an unsaturated hydrocarbon?

Which statement best defines an unsaturated hydrocarbon?

• A. Hydrocarbon with one or more double or triple bonds
• B. Hydrocarbon with only single bonds
• C. Hydrocarbon with no carbon atoms
• D. Aromatic ring contains only single bonds

Answer: (A)

An unsaturated hydrocarbon is one that contains one or more carbon–carbon double or triple bonds. Those multiple bonds mean fewer hydrogens are attached to the carbon skeleton compared with a saturated hydrocarbon that has only single bonds. This makes unsaturated hydrocarbons reactive in addition reactions, where atoms can add across the double or triple bond. The other statements don’t fit: a hydrocarbon with only single bonds is saturated; a hydrocarbon with no carbon atoms isn’t a hydrocarbon; and an aromatic ring isn’t simply single bonds—benzene-like rings have delocalized pi bonds and are considered unsaturated as well.

An unsaturated hydrocarbon is one that contains one or more carbon–carbon double or triple bonds. Those multiple bonds mean fewer hydrogens are attached to the carbon skeleton compared with a saturated hydrocarbon that has only single bonds. This makes unsaturated hydrocarbons reactive in addition reactions, where atoms can add across the double or triple bond. The other statements don’t fit: a hydrocarbon with only single bonds is saturated; a hydrocarbon with no carbon atoms isn’t a hydrocarbon; and an aromatic ring isn’t simply single bonds—benzene-like rings have delocalized pi bonds and are considered unsaturated as well.