See image — Isomerism and Stereochemistry Chemistry Question

💡 Solution & Explanation

# Why Boat Form of Cyclohexane is Less Stable Than Chair Form **Step 1: Understand the conformations** Cyclohexane exists primarily in two conformations: - **Chair form**: All C-H bonds are either axial or equatorial; no strain - **Boat form**: Two carbons are elevated; creates a different geometry **Step 2: Identify the key destabilizing factor in boat form** In the boat conformation, the two "flagpole" hydrogens at the bow and stern positions are positioned very close to each other (only ~1.8 Å apart, within van der Waals contact distance). **Step 3: Explain the unfavorable interaction** These flagpole hydrogens experience **severe steric repulsion** (1,4-diaxial-like interaction) because they are in close proximity. This creates van der Waals strain and electrostatic repulsion between electron clouds. **Step 4: Contrast with chair form** In the chair conformation, all hydrogens are properly distributed with no such close contacts. The axial and equatorial positions minimize steric clashes. **Answer: (B) Due to interaction of flag pole H in boat form.** The flagpole hydrogens create significant steric strain that destabilizes the boat form. Options (A) and (C) are irrelevant to conformational stability in the gas phase or solution.