Question

Which of the following compounds will exhibit $cis-trans$ (geometrical ) isomerism?

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

Answer 1

The correct option is A 2-butene

The restricted rotation of an atom or groups around the doubly bonded carbon gives different geometries of a compound. Such compounds are called geometrical isomers. This isomerism is also known as cis-trans isomerism. The compounds with each doubly bonded carbon attached to two different groups exhibit cis-trans isomerism. However, even though there is restricted rotation for triple bond, alkynes do not exhibit geometrical isomerism, since the triply bonded carbons are attached to one group each only.

Hence, the correct answer is option (a).