Identify the pairs below that represent valid sets of resonance structures for a single molecule or — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

The allyl cation structures (B) and Kekule benzene structures (C) only involve the movement of $\pi$ electrons, fulfilling resonance rules. Pair A represents tautomers (a hydrogen atom physically moves). Pair D represents constitutional isomers (different skeletal connectivity).