Question

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

• A. (a) has high boiling point than (b)
• B. (b) has high boiling point than (a)
• C. (b) has high dipole moment than (a)
• D. (a) has high dipole moment than (b)

Answer 1

Answer: (B), (C)

(b) has high dipole moment than (a)

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

Molecules with higher polarity have stronger intermolecular forces of attraction. A large amount of heat is required to overcome the intermolecular forces of attraction. Hence, these molecules have high boiling points.
Isomer with higher dipole moment will have strong intermolecular force of attraction. Here, trans form has the more dipole moment so it has higher boiling point than its cis isomer.