MHTCET 13 Apr 2026 Shift 2 Paper

Concept:Carbocation stability is governed by the electron-donating ability of alkyl groups through the $+I$ effect and hyperconjugation.Explanation:A carbocation has a positively charged carbon with only six electrons, making it electron-deficient.Alkyl groups donate electron density to this carbon, which stabilises the positive charge.Therefore, the stability order is: $3^{\circ} > 2^{\circ} > 1^{\circ} >$ methyl.Now classify the given options:$\mathrm{CH}_{3}^{+}$ is a methyl carbocation.$\mathrm{CH}_{3}-\mathrm{CH}_{2}^{+}$ is a primary carbocation.$\left(\mathrm{CH}_{3}\right)_{2}\mathrm{CH}^{+}$ is a secondary carbocation.$\left(\mathrm{CH}_{3}\right)_{3}\mathrm{C}^{+}$ is a tertiary carbocation.A tertiary carbocation has three alkyl groups attached to the positively charged carbon, giving maximum stabilisation.Hence, $\left(\mathrm{CH}_{3}\right)_{3}\mathrm{C}^{+}$ is the most stable carbocation.Answer:The most stable carbocation is $\left(\mathrm{CH}_{3}\right)_{3}\mathrm{C}^{+}$, which corresponds to Option D.