See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

**Understanding Resonance Effect and Group Behavior:** Resonance effect occurs when a group attached to benzene can donate or withdraw electron density through delocalization of π-electrons into/out of the aromatic ring. **Analysis of Each Group:** **(A) $-NH_2$ (Aniline):** - Nitrogen has a lone pair on sp² hybridized atom - Lone pair can delocalize into the benzene ring π-system - **Strong resonance effect present** (electron-donating, +R effect) **(B) $-NH_3^+$ (Anilinium ion):** - Nitrogen is positively charged (sp³ hybridized) - No lone pair available for delocalization - The positive charge actually withdraws electrons through inductive effect - **No resonance effect possible** — the lone pair is lost upon protonation - Resonance requires electron density to be shared; here the orbital is empty **(C) $-OH$ (Phenol):** - Oxygen has lone pairs on sp² hybridized atom - Lone pairs readily delocalize into benzene ring - **Strong resonance effect present** (electron-donating, +R effect) **(D) $-Cl$ (Chlorobenzene):** - Chlorine has lone pairs on sp² hybridized atom - Though weakly, can delocalize into benzene ring - **Resonance effect present** (electron-donating, +R effect, though weak due to electronegativity) **Answer: (B)** — The $-NH_3^+$ group cannot exhibit resonance because the nitrogen atom lacks the lone pair needed for π-electron delocalization. It only shows an inductive effect.