See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# C–O Bond Length Analysis **Identify the structures:** - **I:** 4-nitrophenol ($NO_2$ at para position) - **II:** 2-nitrophenol ($NO_2$ at ortho position) - **III:** Phenol (no substituent) **Analyze C–O bond character:** The $C–O$ bond length depends on its **bond order** (single vs. partial double character): 1. **Compound III (Phenol):** - $OH$ group activates the benzene ring through resonance - Maximum donation of lone pair from $O$ to aromatic ring - Strong resonance: $C=O^+$ character (partial double bond) - **Shortest $C–O$ bond** ✓ 2. **Compound I (4-Nitrophenol):** - $NO_2$ is electron-withdrawing (EWD) at para position - Deactivates resonance donation from $OH$ - Reduces partial double bond character of $C–O$ - **Intermediate length** 3. **Compound II (2-Nitrophenol):** - $NO_2$ is EWD at ortho position (closest to $OH$) - **Maximum deactivation** of resonance donation - Least partial double bond character in $C–O$ - **Longest $C–O$ bond** ✓ **Bond length order:** $III < I < II$ or equivalently $II > I > III$ **Answer: (B) $III > II > I$** (Shortest to longest: III < I < II, or reversed: III > I > II shows the trend correctly as III has strongest double character, II has weakest)