See image — GOC and Organic Chemistry Basics Chemistry Question

💡 Solution & Explanation

**Analysis of Melting Points for Chlorobenzene Derivatives:** **Step 1: Understand the structural isomers** - Chlorobenzene: one $Cl$ atom on benzene ring - o-dichlorobenzene: two $Cl$ atoms at **ortho positions** (1,2-) - m-dichlorobenzene: two $Cl$ atoms at **meta positions** (1,3-) - p-dichlorobenzene: two $Cl$ atoms at **para positions** (1,4-) **Step 2: Consider intermolecular forces** All are nonpolar or slightly polar molecules with similar molecular weights. Melting point depends on **crystal packing efficiency** and **van der Waals forces**. Molecules that pack more efficiently in the solid state have higher melting points. **Step 3: Evaluate symmetry and packing** - **p-dichlorobenzene** has **maximum symmetry** (planar, symmetric structure with $Cl$ atoms diametrically opposite) - This high symmetry allows optimal crystal packing in a regular, organized lattice - Symmetric molecules generally have stronger intermolecular interactions in the solid state **Step 4: Compare melting points** - Chlorobenzene: ~−45°C - o-dichlorobenzene: ~−17°C - m-dichlorobenzene: ~−24°C - **p-dichlorobenzene: ~53°C** ✓ **Conclusion:** p-dichlorobenzene has the **maximum melting point** due to its superior molecular symmetry enabling efficient crystal packing and maximum van der Waals interactions in the solid state. **Answer: (D) p-dichlorobenzene**