Question

Which of the following statement(s) is/are true for the given isomers?

• A. (b) has higher melting point than (a)
• B. (a) has higher melting point than (b)
• C. (a) has higher dipole moment than (b)
• D. (b) has higher dipole moment than (a)

Answer 1

Answer: (B), (C)

(a) has higher dipole moment than (b)

In (a), dipole moments of the terminal groups in the trans-isomer add up more than in the cis-isomer. Hence, (a) has higher dipole moment than (b).

Symmetric molecules have better packing efficiency in the crystal lattice when compared to the molecules of similar structure but with lower symmetry.
Hence, molecules with better packing have higher melting points.
Trans-isomer is more symmetrical than the cis-isomer. Thus, (a) has higher melting point than (b)