See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

Concept: Resonating structures (resonance structures) must have the same molecular formula, the same connectivity of atoms (same sigma framework), the same net charge, and differ only in the distribution of electrons (pi electrons and lone pairs). Step 1: Identify what resonating structures must satisfy. - Same atoms bonded in the same order (same connectivity/skeleton) - Same total number of electrons - Same net charge - Only pi electrons and lone pairs are redistributed Step 2: Analyze option (b). First structure: H-O(+)=C=N(-): - Connectivity: H-O-C-N - O has a positive formal charge, N has a negative formal charge, net charge = 0 - O is double-bonded to C, C is double-bonded to N (cumulated double bonds) Second structure: H-O-C≡N: - Connectivity: H-O-C-N - O has lone pairs (neutral), N has a lone pair (neutral), net charge = 0 - O is single-bonded to C, C is triple-bonded to N Both structures have the same atomic connectivity (H-O-C-N), same molecular formula, same net charge (0), and differ only in the distribution of pi electrons and lone pairs. This satisfies all criteria for resonance structures. Step 3: Analyze why other options fail. (a) First structure: H-C≡N(+)-O(-) — connectivity is H-C-N-O. Second structure: H-O-C≡N — connectivity is H-O-C-N. The atomic connectivity is different (H is attached to C in one, to O in the other), so these are not resonance structures but constitutional isomers. (c) First structure: H-C≡N(+)-O(-) — connectivity H-C-N-O. Second structure: H-C(=O)-N: — connectivity H-C(O)-N, with O double bonded to C and N attached to C. The connectivity differs from the first structure, so not resonance structures. (d) First structure: H-O-C≡N(-) — connectivity H-O-C-N. Second structure: H-N=C=O — connectivity H-N-C-O. Different atomic connectivity (H attached to O vs H attached to N), so these are not resonance structures. Step 4: Conclusion. Only option (b) presents two structures with identical atomic connectivity (H-O-C-N), same net charge, and electron redistribution only, making them valid resonating structures. Therefore, the correct answer is B.