See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Plane of Symmetry Analysis A plane of symmetry divides a molecule into two mirror-image halves. **Option (A):** Chiral center present (stereocenter with four different groups: $CH_3$, $COOH$, $H$, $CH_3$). No plane of symmetry. ✗ **Option (B):** Decalin (bicyclic system). The two rings are fused asymmetrically with a methyl substituent at one position only. No plane of symmetry. ✗ **Option (C):** Bicyclic structure with $OH$, $COOH$ groups and stereogenic centers. The substituents are arranged asymmetrically on the bicyclic framework. No plane of symmetry. ✗ **Option (D):** Bicyclic (benzocyclobutene) with two phenyl groups and two $COOH$ groups positioned symmetrically: - The two phenyl groups are equivalent (one on each side) - The two $COOH$ groups are equivalent (one on each side) - A vertical plane passes through the middle of the four-membered ring, creating mirror-image halves The molecule has a **mirror plane of symmetry** perpendicular to the ring system. ✓ **Answer: (D)** is correct because the symmetric placement of identical substituents allows for a plane that divides the molecule into two superimposable mirror images.