Question

p – dichlorobenzene has a higher melting point than those of o – and m – dichlorobenzene.

Answer 1

p – dichlorobenzene has a higher melting point than those of o – and m – dichloro benzene. The higher melting point of p – isomer is due to its symmetry which leads to more close packing of its molecules in the crystal lattice and consequently strong intermolecular attractive force which requires more energy for melting. p – Dihalo benzene > o – Dichloro benzene> m – Dichioro benzene.

Melting point: 323 K 256 K 249 K