See image — Hydrocarbons Chemistry Question

💡 Solution & Explanation

Concept: Conformational analysis of ethane involves rotating around the C-C single bond to produce different spatial arrangements of hydrogen atoms. The potential energy of each conformation depends on torsional strain (repulsion between electron clouds of C-H bonds) and steric interactions. Reasoning: 1. In the eclipsed conformation, the C-H bonds on adjacent carbons are aligned (dihedral angle = 0°), maximizing torsional strain and electron-cloud repulsion, giving the highest potential energy. 2. In the staggered conformation, the C-H bonds are perfectly offset (dihedral angle = 60°), maximizing the distance between bonding electron pairs and minimizing torsional strain, giving the lowest potential energy (~12 kJ/mol lower than eclipsed). 3. Skew (gauche) conformations are intermediate between fully staggered and eclipsed, so they have intermediate potential energy, not the lowest. 4. All conformations do not have equal potential energy; there is a well-established energy barrier between eclipsed and staggered forms. Why other options fail: - (a) Eclipsed: highest potential energy, not lowest. - (b) Skew: intermediate energy, not the minimum. - (d) All equal: incorrect; conformations differ in potential energy due to torsional strain. Therefore, the correct answer is C.