Which of the following compounds shows geometrical isomerism?

Solution

1. Geometrical isomerism requires that each carbon atom of the double bond is bonded to two distinct groups.
2. In ${\text{CH}}_3\text{CH}={\text{CHCH}}_3$, each double-bonded carbon is attached to a hydrogen atom and a methyl group.
3. In 2-methylbut-2-ene and 2-methylpropene, one carbon is attached to two identical methyl groups.
4. In but-1-ene, the terminal carbon is attached to two identical hydrogen atoms.
5. Hence the answer is (B).