Question

The correct relation between the bond lengths of (a) and (b) is:

• A. a = b
• B. b > a
• C. b< a
• D. Impossible to predict

Answer 1

The correct option is B b > a

Both 'a' and 'b' are the bond between C and O. But they have different bond length. Here the lone pair of electrons on O involve in resonance with the carbonyl group.

Due to resonance, this bond will obtain a partial double bond characters. Since we know double bonds are smaller in length compare to single bond, bond length of 'a' is smaller than bond length of 'b'.
Therefore, option (b) is correct.