Multiple choice Which of the following is a flammable polycyclic hydrocarbon? Indazole Indole Benzimidazole Indene Reveal answer Fill a bubble to check yourself D Correct answer Explanation Indene is a flammable polycyclic hydrocarbon. It is composed of a benzene ring fused with a cyclopentene ring. This aromatic liquid is colourless although samples often are pale yellow.