See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

# Analysis of Statement (C) **The key difference:** In phenol, the oxygen is bonded to an aromatic benzene ring, while in methanol, it's bonded to an aliphatic carbon. **Resonance in phenol:** The oxygen in phenol participates in resonance with the benzene ring π-electrons: $$\text{Phenol} \leftrightarrow \text{Resonance structures with }C=O\text{ character}$$ This resonance delocalizes electron density into the ring and creates partial double-bond character in the $C-O$ bond. **Bond length comparison:** - **Phenol $C-O$**: Partial double-bond character ($\sim 1.36$ Å) — **shorter** - **Methanol $C-O$**: Pure single bond ($\sim 1.43$ Å) — **longer** **Why statement (C) is incorrect:** It claims methanol's $C-O$ bond is **shorter** than phenol's, but the actual trend is opposite. Resonance stabilization in phenol creates shorter $C-O$ bond length compared to the aliphatic $C-O$ in methanol. **Other statements are correct:** - (A) ✓ Alcohols ($pK_a \sim 15$) are weaker acids than water ($pK_a = 14$) - (B) ✓ Acid strength decreases with increasing alkyl substitution (inductive effect) - (D) ✓ $\angle C-O-H$ in methanol is indeed $\sim 108.9°$ (tetrahedral geometry) **Answer: (C)**