Question

Which of the following compounds exhibit geometrical isomerism?

• A.
• B.
• C.
• D.

Answer 1

The correct option is A

Geometrical Isomerism arises due to different arrangement of atoms/groups around a system where free rotation of bonds is restricted.

Conditions for Geometrical Isomerism:
1. Free rotation must be restricted
2. Both the terminals of the system must be attached with different atoms/groups.

In alkanes, there is no restriction in rotation. The carbon atoms connected through $\alpha$-bond can rotate easily about it. Hence, compound (d) does not show geometrical isomerism.

Although alkynes have restricted rotation about triple bond it doesnot show geometrical isomerism because they have only one group at the terminals.

In compound (d), terminals of the system have same hydrogen atoms.

In compound (d), both the terminals of system are attached to different groups. Hence, it exhibit geometrical isomerism.