Among the following, the least stable resonance structure is
(A)(see structure)✓ Correct
(B)(see structure)
(C)(see structure)
(D)(see structure)
Answer: (A)
Solution
The least stable resonance structure is the one with like charges (both positive or both negative) on adjacent atoms, which creates strong electrostatic repulsion. Among the given structures, option (A) has positive and negative charges on nearest positions, making it the least stable due to charge-charge repulsion at close proximity. The other structures have better charge separation or delocalization, making them more stable.
JEE Advanced · 2007 · 08 Apr 2007 · Paper 2 · Single correct option