See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

Concept: A molecule has a plane of symmetry (mirror plane) if there exists a plane that divides the molecule into two halves that are mirror images of each other. A molecule with a plane of symmetry is achiral (it is a meso compound or otherwise symmetric). Step 1: Analyze option (c). Structure (c) shows a six-membered ring with four substituents - two carbons on top each bearing H (wedge) and cyclopropyl (wedge, i.e., both pointing up/same face), and two carbons on the bottom each bearing H (wedge) and cyclopropyl (pointing down/opposite face). The molecule has a horizontal plane of symmetry passing through the middle of the ring (between the top two and bottom two carbons), OR a vertical plane of symmetry bisecting the left and right halves. In structure (c), the top two carbons are mirror images of the bottom two carbons through a horizontal plane, making it a meso compound with an internal plane of symmetry. Therefore, (c) has a plane of symmetry. Step 2: Analyze option (a). Structure (a) shows a cyclohexane with cyclopropyl groups and H atoms arranged such that the cyclopropyl groups are all on the same face (all wedge or all dash relative to the ring plane). This is an all-cis arrangement. While it may have a C3 rotation axis, the three-dimensional arrangement of groups in structure (a) - with the depicted geometry - does not create an internal mirror plane that maps the molecule onto itself. The structure is chiral (no plane of symmetry). Step 3: Analyze option (b). Structure (b) shows an asymmetric arrangement of cyclopropyl and H groups around the ring (two cyclopropyl on one side, one on the other in a specific pattern). This arrangement lacks a plane of symmetry and represents a chiral molecule. Step 4: Conclusion. Only structure (c) possesses a plane of symmetry due to its symmetric meso-like arrangement where one half of the molecule is the mirror image of the other half through an internal mirror plane. Therefore, the correct answer is C.