Question

Compare the relative stability of the following resonating structures:

• A. (i) > (ii) > (iii)
• B. (ii) > (i) > (iii)
• C. (i) > (iii) > (ii)
• D. (ii) > (iii) > (i)

Answer 1

The correct option is A (i) > (ii) > (iii)

Since structure (i) is a neutral molecule, it is most stable among the three. In structure (ii), the more electronegative element i.e. oxygen has the negative charge. Therefore, structure (ii) is more stable than structure (iii). Also in structure (ii), the oppositite charges are closer to each other which makes it more stable than the structure (iii).
Hence the correct order for the stability is:
(i) > (ii) > (iii)