In which pairs, the first ion is more stable than the second?

### Related Formula textStability propto textDelocalization of charge via resonance, mesomeric, and back-bonding effects$$\text{Stability} \propto \text{Delocalization of charge via resonance, mesomeric, and back-bonding effects}$$ ### Core Logic Evaluating each specific structural pair: - **Pair (A):** The first carbocation is stabilized by strong +M$+M$ back-bonding from the methoxy (-OMe$-OMe$) oxygen lone pair, making it significantly more stable than the second. - **Pair (B):** The first carbanion is strongly stabilized by the -M$-M$ and -I$-I$ electronic effects of the nitro (-NO_2$-NO_2$) group situated at the ortho position, whereas a carbocation in that spot would be destabilized. Thus, the first ion is more stable. - **Pair (C):** The second cation has extended allylic resonance stabilization, meaning the first is less stable. - **Pair (D):** Cation with -OMe$-OMe$ backbonding is more stable than tertiary aliphatic carbocation, making the first less stable than the second. Thus, only in **(A) & (B)** is the first ion more stable than the second. ### Pattern Recognition Back-bonding from an adjacent oxygen lone pair always triumphs over standard inductive or hyperconjugative alkyl stability templates. For carbanions, ensure electron-withdrawing groups like -NO_2$-NO_2$ match the sign of the charge. ### Evaluation Rubric / Model Answer null ### Chapter Mix Class 11 Chemistry: Some Basic Principles of Organic Chemistry