Question

Which of the following bond, rotation is not permitted by conformational isomerism at room temperature?

• A. $C\equiv C$ bond
• B. $C=C$bond
• C. $C-C$ bond
• D. (a) and (b) above.

Answer 1

The correct option is D (a) and (b) above.

If two different 3D arrangements in space of the atoms in a molecule are interconvertible merely by free rotation
about bonds, they are called conformations.
t permits free rotation (at room temperature) about σ bond only, C-C/ C-N/ C-O/ N-N/ O-O etc. So, the correct answer will be option (d).