See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Analysis of Boiling Points of Dihydroxy and Hydroxy Benzenes **Key Factor: Hydrogen Bonding Strength** The boiling point depends primarily on intermolecular hydrogen bonding: **Compound Structure & H-bonding:** - **I (1,2-dihydroxy benzene):** Ortho-positioned $-OH$ groups → **intramolecular H-bonding** (forms cyclic structure within molecule) - **II (1,3-dihydroxy benzene):** Meta-positioned $-OH$ groups → **moderate intermolecular H-bonding** - **III (1,4-dihydroxy benzene):** Para-positioned $-OH$ groups → **strong intermolecular H-bonding** (linear, ordered arrangement) - **IV (Hydroxy benzene/Phenol):** Single $-OH$ group → **weakest H-bonding** (one donor/acceptor) **Effect on Boiling Point:** Intramolecular H-bonding (Compound I) reduces intermolecular forces, lowering bp. Para-isomer (III) has the most effective intermolecular H-bonding due to symmetric, ordered packing. Meta-isomer (II) has better intermolecular H-bonding than ortho. Phenol (IV) has the least. **Increasing Order:** $$IV \text{ (phenol)} < I \text{ (ortho)} < II \text{ (meta)} < III \text{ (para)}$$ **Answer: (C) IV < I < II < III** ✓