Question

The isomer of dichlorobenzene which has highest boiling point

• A. 1,2 dichlorobenzene
• B. m-dichlorobenzene
• C. p-dichlorobenzene
• D. o-dichlorobenzene

Answer 1

The boiling point of o-dichlorobenzene is greater than the boiling point of m -and p-dichlorobenzenes due to its greater polar nature. The boiling point order is: o−>m−>p− dichlorobenzene.

Melting points of p- dichlorobenzene is greater than that of o- and m-dichlorobenzenes. It is due to the symmetry of the para-isomer of dichlorobenzene that fits in crystal lattice better as compared to o- and m-isomers.

Melting points decrease in the order : p−>o−>m− dichlorobenzene.

Conclusion: The correct option is (D): P-dichlorobenzene is the isomer of dichlorobenzene which has highest boiling point