Question

Identify the correct statements with respect to cis/trans -2- butene from the following

I. cis-2- Butene is more polar than trans -2 Butene II. Melting point of cis-2- Butene is greater than that of trans -2- Butene III. Boiling point of cis-2- Butene is greater than that of trans -2- Butene

• A. I and II only
• B. I and III only
• C. II and III only
• D. I, II and III

Answer 1

Answer: (B)

I and III only

Answer 2

Statement I: cis-2-butene is polar due to the asymmetrical arrangement of methyl groups, resulting in a net dipole moment. trans-2-butene is nonpolar as the dipoles cancel out due to symmetry.

Statement II: trans isomers generally pack more efficiently due to their symmetry, leading to stronger intermolecular forces and a higher melting point compared to cis isomers.

Statement III: cis-2-butene has a higher boiling point because its polarity (dipole-dipole interactions) contributes to stronger intermolecular forces than the London dispersion forces present in nonpolar trans-2-butene.