See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

**Step 1: Understand electron withdrawal in resonance** Groups can withdraw electrons from the benzene ring through resonance by either: - Being electron-deficient (accepting electrons) - Having lone pairs that can delocalize while withdrawing σ-electron density **Step 2: Analyze each group** **(A) -Ph (Phenyl):** Can donate electrons to benzene via resonance through its π-electrons. This is an electron-donating group, not withdrawing. ✗ **(B) -N⁺Me₃ (Trimethylammonium):** Positive charge makes this strongly electron-withdrawing, but it withdraws electrons *continuously* through the inductive effect, not just a "pair" in resonance. ✗ **(C) -CONH₂ (Primary amide):** - The carbonyl carbon is electron-deficient and can accept electrons - The nitrogen lone pair can participate in resonance: $$\text{C}=\text{O} \longleftrightarrow \text{C}^-\text{-O}^+$$ - This allows the amide to withdraw **exactly one pair of electrons** via resonance while maintaining the benzene ring's aromaticity - This is a **weak** electron-withdrawing group that operates through resonance only ✓ **(D) None:** Incorrect since (C) fits the criteria. **Answer: (C)** — The primary amide group uniquely withdraws electron density through resonance (via the carbonyl) without being a strong inductive withdrawer, making it capable of withdrawing precisely one electron pair while preserving benzene's aromatic character.