Which of the following pairs of structures are resonance structures?

Question

Quizplus · Accepted Answer

Structures 1 and 2 only differ in the placement of a lone pair of electrons, which can be represented by a resonance structure. Structures 3 and 4 only differ in the location of a double bond, which can also be represented by a resonance structure. However, structures 1-4 cannot be interconverted through the movement of pi electrons, which is a requirement for true resonance structures. Therefore, only structures 1 and 2 and structures 3 and 4 are resonance structures, making choice C the correct answer.

Which of the Following Pairs of Structures Are Resonance Structures