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Saturday, 31 October

JEE Main · Chemistry · Haloalkanes and Haloarenes

Temperature Effects on Substitution vs Elimination

JEE Main asked Temperature Effects on Substitution vs Elimination 3 times in 3 of the 108 shifts Lumi analysed, in 2020 and 2024. It belongs to SN1 and SN2 Mechanisms, in Haloalkanes and Haloarenes (Chemistry). The longest wait between two years asking it was 4 years. In 2024 it came in more than one shift of the same year.

Updated 2026-10-24

Times asked
3
in 3 shifts
Years
2 of 8
First asked
2020
last in 2024
Pattern
Occasional
across the analysed shifts

Questions on this idea a shift, by year

2017–2026. Asked in 2020 and 2024. Years differ in how many shifts Lumi analysed, so each year is scaled to one shift of 25 Chemistry questions.

00.050.10’170.08’200’210’220’230.09’240’250’26

Raw count: 2017: 0 in 1 shift · 2020: 1 in 12 shifts · 2021: 0 in 24 shifts · 2022: 0 in 24 shifts · 2023: 0 in 12 shifts · 2024: 2 in 18 shifts · 2025: 0 in 8 shifts · 2026: 0 in 9 shifts.

Shift by shift

Each square is one analysed shift, in date order. Open a filled one for that paper.

  • 20260 of 9
  • 20250 of 8
  • 20242 of 18
  • 20230 of 12
  • 20220 of 24
  • 20210 of 24
  • 20201 of 12
  • 20170 of 1

Asked in that shift More than once Not asked

How JEE Main framed it

Diagram based is the usual form. Skill tested: application.

  • Count atoms in two products
  • Major alkene from dehydrobromination with alcoholic koh

Difficulty

Easy 1Medium 2Hard 0

1 of the 3 questions had a numerical answer.

Every question

All 3 questions

From the official JEE Main shift papers, newest first. Open one for the full question, the options and the official answer.

  1. 31 Jan 2024, Shift 1 · Q88CH3CH2Br+NaOH\mathrm{CH_3CH_2Br + NaOH} with C2H5OH\mathrm{C_2H_5OH} gives Product A, and with H2O\mathrm{H_2O} gives Product B. The total number of…EasyNumerical valueHas a figure
  2. 4 Apr 2024, Shift 2 · Q77→ΔKOH(alc)\xrightarrow[\Delta]{\mathrm{KOH(alc)}} major product "P" Product P isMediumDiagram basedHas a figure
  3. 3 Sep 2020, Shift 2 · Q45The major product in the following reaction is : [figure] →Heatt-BuOH\xrightarrow[\text{Heat}]{\text{t-BuOH}}MediumDiagram basedHas a figure

Shifts: 3 Sep 2020, Shift 2, 31 Jan 2024, Shift 1, 4 Apr 2024, Shift 2.

Same topic

Other ideas in SN1 and SN2 Mechanisms

SN1 and SN2 Mechanisms has 19 ideas JEE Main has asked; 12 of them came up in more than one question. The 12 most asked are below.

Topic analysisChapter analysisStudy this chapterAll repeated ideas