See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Canonical Structures: Understanding the Correct Statement **Step 1: Define canonical structures** Canonical structures (resonance structures) are different Lewis structures of the same molecule that differ only in electron distribution, not in nuclear positions. **Step 2: Analyze each option** **(A) Same number of unpaired electrons** — FALSE Different canonical structures can have different distributions of electrons. While total valence electrons are conserved, unpaired electrons can vary between structures (e.g., in $O_3$, one structure has unpaired electrons distributed differently). **(B) Different numbers of paired electrons** — FALSE This contradicts electron conservation. Total electrons remain constant; only their distribution changes. **(D) Always equivalent** — FALSE Canonical structures often differ in stability. For example, in benzene, Kekulé structures are equivalent, but in molecules like $NO_2^-$, contributing structures have different stabilities. **Step 3: Validate option (C)** $$\text{Same total electrons} \Rightarrow \text{Same unpaired electron count (total)}$$ Different canonical structures need not be equivalent in stability or geometry, BUT they should not differ dramatically in stability. If one structure is far more stable, it dominates and others contribute minimally. Valid canonical structures have comparable (not vastly different) stabilities to significantly contribute to the hybrid. **Answer: (C)** — Canonical structures need not always be equivalent, but they should not differ much in stability to be meaningful contributors to the actual resonance hybrid.