Which of the following are pairs of contributing structures?

Question

Quizplus · Accepted Answer

The contributing structures for this molecule are:
I - O=C-OH
II - O^-C=O+
III - -OH
IV - O^-=C-OH
Structures I and II do not contribute equally to the resonance hybrid because structure II has a positive charge on oxygen, which is electronegative, making it less stable. Structures III and IV also do not contribute equally because structure IV has a negative charge on the more electronegative oxygen atom, making it less stable. Therefore, only structures I and IV contribute significantly to the resonance hybrid, making the correct answer choice C.

Which of the Following Are Pairs of Contributing Structures