Question

Which of the following will show geometrical isomerism?

• A. 2-methylbut-2-ene
• B. 2-methylpropene
• C. Cyclohexene
• D. 1,2-dibromopropene

Hint:

Geometrical isomerism can be observed in compounds with a double bond (alkenes) or rings where different substituents are attached to the carbons or atoms involve(D) The key requirement is that the substituents must allow for different spatial orientations (cis or trans).

Answer 1

The Correct Option is D

Geometrical isomerism (cis-trans isomerism) arises in compounds that have restricted rotation around a double bond or a ring system, typically involving alkenes or cyclic compounds where two substituents are attached to a double bond or ring. - Option A: 2-methylbut-2-ene has a double bond between two carbon atoms (C=C) with different groups attached, making it a compound that can show cis-trans isomerism. - Option B: 2-methylpropene has a double bond but the two groups on the same carbon (C=CH2) do not allow for cis-trans isomerism due to identical substituents. - Option C: Cyclohexene does not exhibit cis-trans isomerism because its double bond is part of a cyclic structure, and there is no opportunity for the type of substitution that allows for such isomerism. - Option D: 1,2-dibromopropene is a compound that exhibits geometrical isomerism. The bromine atoms are attached to different carbons of the double bond (C=C), and the two positions can lead to cis (both bromines on the same side) and trans (bromines on opposite sides) isomerism. Thus, 1,2-dibromopropene shows geometrical isomerism.