Question

Which of the following compounds shows geometrical isomerism?

• A. 4-methyl-pent-2-ene
• B. 2-methyl-pent-2-ene
• C. 4-methyl-pent-1-ene

Answer 1

The correct option is A

4-methyl-pent-2-ene

Explanation for correct option:

Option (A)
4-methylpent-2-ene has restricted rotation (due to a double bond) and has different substituents attached to the doubly bonded carbon atoms. That is why it exhibits geometrical isomerism. Its geometrical isomers are as shown

Explanation of incorrect options:

Option (B):
2-methylpent-2-ene has two methyl groups attached to one of the doubly bonded carbon atom. Therefore, it does not show geometrical isomerism.

Option (C):
4-methyl-pent-1-ene has two hydrogen atoms attached to one of the doubly bonded carbon atoms. Therefore, it does not show geometrical isomerism.

Hence, option (A) is the correct answer.