See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# C–N Bond Length Analysis **Identify the C–N bonds in each compound:** - **I:** Aromatic $C(\text{benzene})-NH_2$ — partial double bond character (resonance) - **II:** Aromatic $C(\text{benzene})-NH_2$ — partial double bond character (resonance) - **III:** Aliphatic $C(\text{sp}^3)-NH_2$ — pure single bond - **IV:** $C=NH$ — pure double bond **Bond length trend:** $$C=N \text{ (double)} < C-N \text{ (aromatic/resonance)} < C-N \text{ (aliphatic single)}$$ Typical values: - $C=N$: ~1.28 Å - Aromatic $C-N$: ~1.34–1.37 Å (partial double bond from resonance) - Aliphatic $C-N$: ~1.47 Å (single bond) **Order from shortest to longest:** $$IV < II \approx I < III$$ Since I and II are both aromatic $C-N$ bonds with similar resonance stabilization, but I also has an aldehyde group that slightly increases electron withdrawal, I is marginally shorter than II. **Therefore:** $III > I > II > IV$ ✓ **The answer is (C).**