Chemistry - STEREO ISOMERISM Question with Solution | TestHub

Question Explanation:

The question asks which compound among the given options does not exhibit geometrical (cis-trans) isomerism.

Concept:

Geometrical Isomerism, Endocyclic Double Bond.

Solution:

Geometrical isomerism requires a double bond with two different groups on each carbon, and the structure of the molecule (such as being in a ring) can affect this. Geometrical (cis-trans) isomerism around a $\mathrm{C}=\mathrm{C}$ bond requires (i) restricted rotation (which a double bond provides) and (ii) two different substituents on each of the ${\mathrm{sp}}^2$ carbons. In endocyclic alkenes (where the $\mathrm{C}=\mathrm{C}$ is part of the ring), the ring itself fixes the relative positions of the substituents. For rings up to 7 members, an endocyclic double bond cannot adopt two distinguishable arrangements (there is only one way to attach the ring), so no cis-trans isomerism is possible. In option D the $\mathrm{C}=\mathrm{C}$ is part of a 6-membered ring (endocyclic), so it cannot show geometrical isomers

Final Answer: Option (D)