MHTCET 26 Apr 2025 Shift 2 Paper

Concept:Alkyl groups stabilize a nearby positive charge through their electron-releasing inductive effect.Explanation:The given species are $\mathrm{NH}_4^+$, $\mathrm{RNH}_3^+$, $\mathrm{R}_2\mathrm{NH}_2^+$, and $\mathrm{R}_3\mathrm{NH}^+$.As the number of alkyl groups bonded to nitrogen increases, the electron density on nitrogen increases.This helps disperse the positive charge and stabilizes the cation.Thus, the stability order is: $\mathrm{NH}_4^+ < \mathrm{RNH}_3^+ < \mathrm{R}_2\mathrm{NH}_2^+ < \mathrm{R}_3\mathrm{NH}^+$.Since $\mathrm{NH}_4^+$ has no alkyl group to donate electron density, its positive charge is least stabilized.Answer:Option A: $\mathrm{NH}_4^+$ is the least stable species.