Question

With respect to the conformers of ethane, which of the following statements is true ?

• A. Bond angle changes but bond length remains same
• B. Both bond angle and bond length change
• C. Both bond angles and bond length remains same
• D. Bond angle remains same but bond length changes

Answer 1

The Correct Option is C

To understand the conformers of ethane, it's essential to know that these are the different spatial arrangements of the molecule that result from rotation around the carbon-carbon (C-C) sigma bond. The concept of conformational isomerism applies here, where the ethane molecule can rotate freely around the C-C bond, giving rise to different conformations or conformers.

Key Explanation:

1. The primary conformations of ethane are the staggered and eclipsed forms. In the staggered conformation, the hydrogen atoms attached to adjacent carbon atoms are positioned as far apart as possible, minimizing torsional strain.
2. In the eclipsed conformation, the hydrogen atoms on adjacent carbons are aligned, leading to higher torsional strain due to repulsive interactions.
3. Despite these different spatial arrangements, the internal bond angles and bond lengths within the ethane molecule remain unchanged. The C-C bond length and the C-H bond lengths are the same in both staggered and eclipsed forms.

Conclusion:

Given this understanding of ethane's conformers, the statement "Both bond angles and bond length remain same" is true. Hence, the correct answer is:

Option: Both bond angles and bond length remain same.