The p-isomer of dichlorobenzene has higher melting point than o-and m-isomer. Why?

Explanation

The melting point of p-isomer of dichlorobenzene is higher than that of or and m-isomers. This is because, p-isomer has symmetrical structure and therefore, its molecules can easily pack closely in crystal lattice. Hence, it has stronger intermolecular forces of attraction than o- and m-iomer. Therefore, greater enerp is required to break the intermolecular forces to melt or dissolve the p-isomer than the corresponding and mr-isomers. In other words, the melting point of p-isomer is higher and its solubility is lower than the corresponding and m-isomers.