Question

A molecule has two bonds of equal length, but its Lewis structure shows one single bond and one double bond. This is best explained by:

• A. Resonance
• B. Hybridisation
• C. Polarisation
• D. Ionization

Hint:

Resonance leads to: \[ \boxed{ \begin{aligned} &\text{Equal bond lengths}\\ &\text{Fractional bond order}\\ &\text{Delocalisation of electrons}\\ &\text{Greater molecular stability} \end{aligned} } \] Common examples: \[ \boxed{O_3,\;CO_3^{2-},\;NO_3^{-},\;NO_2^{-},\;C_6H_6} \]

Answer 1

The Correct Option is A

When two bonds in a molecule are experimentally found to be of equal length yet the Lewis structure predicts one single and one double bond, the molecule is best described as a resonance hybrid of the contributing structures. The actual bond order is intermediate (between 1 and 2) and both bonds are equivalent, as in the carbonate ion or ozone.