Question

From the following, the least stable structure is:
(Assume standard resonance structures)

• A.
• B.
• C.
• D.

Hint:

Octet rule priority: Complete Octet \(>\) Electronegativity considerations.

Answer 1

The Correct Option is D

Step 1: Stability Rules for Resonance:
1. Structures with more covalent bonds (complete octets) are more stable.
2. Positive charge on electropositive atom (C) is better than on electronegative atom (N, O) IF octets are incomplete.
3. HOWEVER, a structure with a positive charge on N or O with a COMPLETE octet is MORE stable than a carbocation with an INCOMPLETE octet.
4. The LEAST stable structures are those with incomplete octets on electronegative atoms or like charges on adjacent atoms.
Step 2: Conclusion:
Without the specific images, the "least stable" is typically a structure violating the octet rule on a highly electronegative atom (like a nitrene cation) or having adjacent positive charges.