JEE Main 2026 — Haloalkanes and Haloarenes Question with Solution
JEE Main 2026 (21 January Shift 2)
Question
The correct order of the rate of the reaction for the following reaction with respect to nucleophiles is :
Choose an option
Show full solutionCorrect option: C
Correct answer
C
Step-by-step explanation
For the SN2 reaction CH₃Br + Nu⁻, nucleophilicity in aprotic solvents is determined by basicity and polarizability.
⁻OH (hydroxide) is the strongest nucleophile and base, making it highly reactive.
PhO⁻ (phenoxide) is a good nucleophile with reasonable basicity.
CH₃COO⁻ (acetate) is weakened by resonance stabilization of its negative charge across the C-O bonds, reducing its nucleophilicity.
ClO₄⁻ (perchlorate) is a very weak nucleophile, being the conjugate base of a strong acid (HClO₄).
The correct order of nucleophilicity is: ⁻OH > PhO⁻ > CH₃COO⁻ > ClO₄⁻, which matches option (3).
⁻OH (hydroxide) is the strongest nucleophile and base, making it highly reactive.
PhO⁻ (phenoxide) is a good nucleophile with reasonable basicity.
CH₃COO⁻ (acetate) is weakened by resonance stabilization of its negative charge across the C-O bonds, reducing its nucleophilicity.
ClO₄⁻ (perchlorate) is a very weak nucleophile, being the conjugate base of a strong acid (HClO₄).
The correct order of nucleophilicity is: ⁻OH > PhO⁻ > CH₃COO⁻ > ClO₄⁻, which matches option (3).
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This is a previous-year question from JEE Main 2026, covering the Haloalkanes and Haloarenes chapter of Chemistry. PrepSharp catalogues every PYQ from JEE Main with a verified answer key and step-by-step solution prepared by IIT alumni — so you can search by chapter, topic or year and revise efficiently.