Relative stability of the contributing structures is : [figure]
- (II) > (I) > (III)
- (III) > (II) > (I)
- (I) > (III) > (II)
- (I) > (II) > (III)
Answer
(4) (I) > (II) > (III)
Solution
(I) has no charge separation and every atom has an octet, so it is the most stable.
(II) has separated charges, but the negative charge is on the more electronegative O and the positive charge on C, so it comes next.
(III) puts the negative charge on C and the positive charge on the more electronegative O, which also has only a sextet, so it is the least stable.
∴ (I) > (II) > (III)
Answer: (4)