Question

Which of the following compounds will exhibit cis-trans isomerism?

• A. 2-butene
• B. 2-butyne
• C. 2-butanol
• D. butanal

Answer 1

The correct option is A 2-butene

The compounds with each doubly bonded carbon attached to two different groups (like Cab=Cab, Cab=Ccd) exhibit geometrical isomerism i.e., cis and trans forms. The geometrical isomerism arises due to the restricted rotation of the double bond.

However, even though there is restricted rotation for a triple bond, alkynes do not exhibit geometrical isomerism, since the triply bonded carbons are attached to only one group each.