See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

**Understanding Electrophiles:** An electrophile is a species that accepts electron pairs (Lewis acid). It must have: - An empty/partially filled orbital capable of accepting electrons - Positive charge or electron-deficient character **Analysis of each species:** **(A) $BCl_3$:** Boron has only 6 electrons in its valence shell (electron-deficient). It readily accepts electron pairs → **Strong electrophile** **(B) $AlCl_3$:** Aluminum has only 6 electrons in its valence shell (electron-deficient). It accepts electron pairs → **Strong electrophile** **(C) $NH_4^+$ (Ammonium ion):** Nitrogen has a complete octet with 8 electrons. All four N-H bonds are formed, and there are no available orbitals to accept additional electron pairs. The positive charge resides on nitrogen, but it cannot accept more electrons due to the filled valence shell → **Cannot act as an electrophile** **(D) $H^+$ (Proton):** A bare proton with empty 1s orbital strongly accepts electron pairs → **Strong electrophile** **Answer: (C) $NH_4^+$** $NH_4^+$ has a complete octet and no vacant orbitals, so it cannot accept electron pairs and therefore cannot function as an electrophile.