JEE Main · Chemistry · Haloalkanes and Haloarenes
SN1 and SN2 Mechanisms: JEE Main previous year questions
47 questions in the 108 JEE Main shifts Lumi analysed, in 8 of 8 years. Pattern: Asked most years. 18 came in 2024–26. Here is how it is asked and which ideas come back.
- Questions
- 47
- in 43 of 108 shifts
- Years asked
- 8/8
- last asked 2026
- Weighted estimate
- 0.4
- model; history: 0.4 a shift on average, typically 0.2–0.6
Key findings
- 01
Asked in 8 of 8 years with analysed shifts and in 43 of 108 shifts: 47 questions, #65 of 196 topics. It came in every year with analysed shifts.
- 02
43% of its questions since 2020 tested an idea no earlier year had asked; 9 repeated an idea from the year before.
- 03
The most repeated idea is Allylic and Benzylic Reactivity in SN1, asked 7 times in 7 shifts (2017, 2021, 2022, 2023, 2026), most often as “statement i/ii on sn1 reactivity”.
- 04
JEE Main has asked 19 of the 49 ideas in this topic; 21 have never been asked, directly or inside another question.
- 05
Mostly asked as diagram based (45%); 6% need a numerical answer, 21% are easy and 21% hard.
- 06
The skill tested most is conceptual (49%), then multi-step (21%).
Questions a shift, year by year
Out of the 25 Chemistry questions in a shift. Years differ in how many shifts Lumi analysed, so each year is scaled to one shift.
Raw count: 2017: 1 in 1 shift · 2020: 6 in 12 shifts · 2021: 6 in 24 shifts · 2022: 8 in 24 shifts · 2023: 8 in 12 shifts · 2024: 13 in 18 shifts · 2025: 1 in 8 shifts · 2026: 4 in 9 shifts.
- Up to 2023
- 0.5
- a shift, of 25
- Since 2024
- 0.4
- -0.1
- Usual gap
- 1.3 yrs
- between years asking it
- Shifts with it
- 43/108
- 40% of analysed shifts
How it is asked
Difficulty, format and skill
Across all 47 questions on SN1 and SN2 Mechanisms since 2017.
Difficulty
QUESTIONS- Easy10 · 21%
- Medium27 · 57%
- Hard10 · 21%
Format
SHARE- Diagram based · 21 Q45%
- Single correct · 8 Q17%
- Other · 5 Q11%
- Two statements · 4 Q9%
- Match the list · 3 Q6%
- Numerical value · 3 Q6%
- Assertion–reason · 3 Q6%
Skill tested
SHARE- Conceptual · 23 Q49%
- Multi-step · 10 Q21%
- Application · 9 Q19%
- Recall · 4 Q9%
- Diagram reading · 1 Q2%
Repeats
New idea, or one asked before?
Each column is a year. Blue questions tested an idea no earlier year had asked; navy ones went back to an idea from an earlier year. 2017 is the first year, so everything in it counts as new. Heights are question counts, and Lumi analysed 1 to 24 shifts a year, so compare the split inside a column rather than heights across years.
- Idea asked for the first time
- Idea asked in an earlier year
Coverage of the topic
JEE Main has asked 19 of the 49 ideas in this topic. 21 have never been asked yet.
- Asked directly19 · 39%
- Touched inside another question9 · 18%
- Never asked21 · 43%
Ideas come from Lumi’s JEE syllabus map. A never-asked idea is not a safe skip: across all of JEE Main, 22% of questions since 2024 tested an idea no earlier year had asked.
Drill down
Chapter, idea, question
Every idea JEE Main tested in this topic, with its eight years. Open one to read the questions.
18 ideas inside
Squares are the 8 years with analysed shifts, 2017 to 2026. A number is the questions that year when there is more than one; the shade is scaled to one shift, so a year with more analysed shifts (1 to 24 a year) does not look darker. Share is of the level above.
Ideas
Every idea inside this topic
19 different ideas were tested; 12 came more than once.
statement i/ii on sn1 reactivity
Diagram based · 7 shifts · 1 numericalmatch list on named reactions
Match the list · 4 shiftspredict product of reaction
Match the list · 4 shiftspredict stereochemical product of substitution sequence
Diagram based · 4 shiftsidentify reaction without carbocation rearrangement
Diagram based · 3 shifts · 1 numericalcount correct statements on alkyl halides
Single correct · 3 shiftsassertion-reason on sn2 reactivity
Diagram based · 3 shiftsorder/ranking of sn2 reactivity
Diagram based · 3 shiftscount atoms in two products
Diagram based · 3 shifts · 1 numericalassertion-reason on ambident nucleophile cyanide
Assertion–reason · 2 shiftsassertion-reason on allyl halides
Assertion–reason · 2 shiftsmost sn1 reactive halogen among structures
Diagram based · 2 shiftsidentify example of vinylic halide
Diagram based · 1 shiftidentify halide unreactive toward agno3
Diagram based · 1 shiftidentify halide inactive toward sn1
Diagram based · 1 shiftnucleophilicity order
Single correct · 1 shiftpredict product of neopentyl halide solvolysis
Other · 1 shiftorder/ranking of reactivity toward aqueous silver nitrate
Diagram based · 1 shifteffect of base concentration on substitution and elimination rates
Single correct · 1 shift
| Idea | Years asked | Times | Shifts | Format | Numerical |
|---|---|---|---|---|---|
| Allylic and Benzylic Reactivity in SN1statement i/ii on sn1 reactivity | 7 | 7 | Diagram basedConceptual | 1 | |
| Finkelstein Reactionmatch list on named reactions | 4 | 4 | Match the listRecall | – | |
| Ambident Nucleophiles (Cyanide/Nitrite)predict product of reaction | 4 | 4 | Match the listConceptual | – | |
| SN2 Transition Statepredict stereochemical product of substitution sequence | 4 | 4 | Diagram basedConceptual | – | |
| Carbocation Rearrangements in SN1identify reaction without carbocation rearrangement | 3 | 3 | Diagram basedMulti-step | 1 | |
| Solvent Effects on Substitutioncount correct statements on alkyl halides | 3 | 3 | Single correctConceptual | – | |
| Allylic and Benzylic Reactivity in SN2assertion-reason on sn2 reactivity | 3 | 3 | Diagram basedConceptual | – | |
| Substrate Steric Effectsorder/ranking of sn2 reactivity | 3 | 3 | Diagram basedApplication | – | |
| Temperature Effects on Substitution vs Eliminationcount atoms in two products | 3 | 3 | Diagram basedApplication | 1 | |
| Ambident Nucleophiles (Cyanide vs Isocyanide)assertion-reason on ambident nucleophile cyanide | 2 | 2 | Assertion–reasonConceptual | – | |
| Reactivity of Allylic and Benzylic Halidesassertion-reason on allyl halides | 2 | 2 | Assertion–reasonApplication | – | |
| SN1 Carbocation Intermediatemost sn1 reactive halogen among structures | 2 | 2 | Diagram basedConceptual | – | |
| Inertness of Vinylic and Aryl Halidesidentify example of vinylic halide | 1 | 1 | Diagram basedDiagram reading | – | |
| Inertness of Vinylic and Aryl Halidesidentify halide unreactive toward agno3 | 1 | 1 | Diagram basedConceptual | – | |
| Bredt's Rule and Bridgehead Halidesidentify halide inactive toward sn1 | 1 | 1 | Diagram basedConceptual | – | |
| Nucleophilicity vs Basicitynucleophilicity order | 1 | 1 | Single correctConceptual | – | |
| Neopentyl Halide Exceptionspredict product of neopentyl halide solvolysis | 1 | 1 | OtherMulti-step | – | |
| Neighboring Group Participation (NGP)order/ranking of reactivity toward aqueous silver nitrate | 1 | 1 | Diagram basedConceptual | – | |
| Rate Law and Concentration Dependenceeffect of base concentration on substitution and elimination rates | 1 | 1 | Single correctConceptual | – |
Times and shifts count every analysed shift. Across JEE Main, 78% of questions since 2024 went back to an idea an earlier year had asked; the rest were new. All repeated ideas
Every question
SN1 and SN2 Mechanisms questions, year by year
The newest 40 show their opening words as they appeared in the official paper; older ones name the idea they tested. Open one for its options and the official answer.
JEE Main 20264 questions in 4 shifts
- 2 Apr, Shift 1Q64Given below are two statements : Statement (I) : Benzyl chloride reacts faster in mechanism than ethyl chloride. Statement…
Idea: Allylic and Benzylic Reactivity in SN1
EasyTwo statements - 2 Apr, Shift 2Q65Correct statements regarding alkyl halides (R - X) among the following are: A. Alcohol being less polar solvent as compared to water,…
Idea: Solvent Effects on Substitution
MediumSingle correct - 4 Apr, Shift 1Q65Match the LIST-I with LIST-II List-I (Name of reaction): A. Finkelstein reaction; B. Swarts reaction; C. Sandmeyer's reaction; D. Fittig…
Idea: Finkelstein Reaction
Asked the year beforeEasyMatch the list - 8 Apr, Shift 2Q63The major product of which of the following reaction is not obtained by rearrangement reaction ?
Idea: Carbocation Rearrangements in SN1
MediumDiagram based · figure
JEE Main 20251 question in 1 shift
- 2 Apr, Shift 2Q67Match List - I with List - II. List - I (Reaction) (A)…
Idea: Finkelstein Reaction
EasyMatch the list · figure
JEE Main 202413 questions in 11 shifts
- 4 Apr, Shift 2Q76Find out the major product formed from the following reaction. [Me : ]
Idea: Allylic and Benzylic Reactivity in SN2
HardDiagram based · figure - 4 Apr, Shift 2Q77major product "P" Product P is
Idea: Temperature Effects on Substitution vs Elimination
MediumDiagram based · figure - 6 Apr, Shift 2Q76Chemical reaction: (1-chloropropyl)cyclohexane [cyclohexyl ring attached to CHCl-CH2-CH3] NaOH Major…
Idea: Carbocation Rearrangements in SN1
Asked the year beforeMediumDiagram based · figure - 8 Apr, Shift 1Q77Which among the following compounds will undergo fastest reaction.
Idea: Substrate Steric Effects
Asked the year beforeEasyDiagram based · figure - 8 Apr, Shift 2Q75Given below are two statements : Statement (I) : reactions are 'stereospecific', indicating that they result in the…
Idea: SN2 Transition State
EasyTwo statements - 9 Apr, Shift 1Q73Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : …
Idea: Allylic and Benzylic Reactivity in SN2
EasyAssertion–reason - 9 Apr, Shift 2Q75[figure: (benzylic carbon bearing CH, next carbon bearing both OCH and Br)]…
Idea: Ambident Nucleophiles (Cyanide/Nitrite)
Asked the year beforeHardSingle correct · figure - 1 Feb, Shift 1Q74Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) : Haloalkanes…
Idea: Ambident Nucleophiles (Cyanide vs Isocyanide)
MediumAssertion–reason - 27 Jan, Shift 1Q73The correct statement regarding nucleophilic substitution reaction in a chiral alkyl halide is :
Idea: SN2 Transition State
EasySingle correct - 30 Jan, Shift 1Q73Example of vinylic halide is :
Idea: Inertness of Vinylic and Aryl Halides
New ideaEasyDiagram based · figure - 30 Jan, Shift 1Q74Given below are two statements : one is labelled as Assertion (A) and the other is labelled as Reason (R). Assertion (A) :…
Idea: Reactivity of Allylic and Benzylic Halides
EasyAssertion–reason - 30 Jan, Shift 2Q75Given below are two statements: Statement - I: High concentration of strong nucleophilic reagent with secondary alkyl halides which do not…
Idea: Solvent Effects on Substitution
Asked the year beforeMediumTwo statements - 31 Jan, Shift 1Q88with gives Product A, and with gives Product B. The total number of…
Idea: Temperature Effects on Substitution vs Elimination
EasyNumerical value · figure
JEE Main 20238 questions in 7 shifts
- 6 Apr, Shift 1Q75For the reaction The correct…
Idea: Finkelstein Reaction
Asked the year beforeHardSingle correct - 8 Apr, Shift 1Q73Choose the halogen which is most reactive towards reaction in the given compounds (A, B, C & D) A. [structure] B.…
Idea: SN1 Carbocation Intermediate
HardDiagram based · figure - 10 Apr, Shift 1Q73Identify the correct order of reactivity for the following pairs towards the respective mechanism (A) [structure:…
Idea: Substrate Steric Effects
MediumOther · figure - 11 Apr, Shift 1Q74[figure: Reaction (I): 4-methoxybenzyl chloride () + Nu gives 4-methoxybenzyl-Nu. Reaction (II):…
Idea: Allylic and Benzylic Reactivity in SN1
Asked the year beforeMediumDiagram based · figure - 11 Apr, Shift 2Q74Compound from the following that will not produce precipitate on reaction with is :
Idea: Inertness of Vinylic and Aryl Halides
New ideaMediumDiagram based · figure - 11 Apr, Shift 2Q90The number of possible isomeric products formed when 3-chloro-1-butene reacts with HCl through carbocation formation is ____________
Idea: Carbocation Rearrangements in SN1
New ideaHardNumerical value - 13 Apr, Shift 1Q752-Methyl propyl bromide reacts with and gives 'A' whereas on reaction with it gives 'B'. The…
Idea: Solvent Effects on Substitution
New ideaMediumSingle correct - 13 Apr, Shift 2Q75Match List I with List II 1 - Bromopropane is reacted with reagents in List I to give product in List II LIST I - Reagent | LIST II -…
Idea: Ambident Nucleophiles (Cyanide/Nitrite)
MediumMatch the list
JEE Main 20228 questions in 8 shifts
- 25 Jul, Shift 1Q74Most stable product of the following reaction is : (i) p-toluenesulfonyl chloride (), Pyridine (ii) NaCN,…
Idea: SN2 Transition State
New ideaMediumDiagram based · figure - 27 Jul, Shift 1Q75[figure: benzene ring (hexagon with inner circle) with CH2OH at the top and OH at the bottom (para)] HCl A…
Idea: Finkelstein Reaction
New ideaMediumDiagram based · figure - 29 Jul, Shift 1Q74[figure: CH3CH2CH2-Cl, a three-carbon chain bearing Cl; left arrow with AgCN, gives 'A' (Major Product); right…
Idea: Ambident Nucleophiles (Cyanide vs Isocyanide)
New ideaMediumDiagram based · figure - 24 Jun, Shift 2Q89Consider the above reaction. The number of electrons present in the product 'P' is ________.
Idea: Allylic and Benzylic Reactivity in SN1
Asked the year beforeMediumNumerical value · figure - 26 Jun, Shift 2Q71The correct order of nucleophilicity is
Idea: Nucleophilicity vs Basicity
New ideaMediumSingle correct - 27 Jun, Shift 1Q75The major product of the following reaction is : [figure: reactant drawn as a benzene ring with a substituent F ortho to a side chain and…
Idea: SN2 Transition State
New ideaMediumDiagram based · figure - 28 Jun, Shift 1Q75Which one of the following compounds is inactive towards reaction ?
Idea: Bredt's Rule and Bridgehead Halides
New ideaMediumDiagram based · figure - 29 Jun, Shift 2Q75Two isomers (A) and (B) with Molar mass 184 g/mol and elemental composition C, 52.2% ; H, 4.9 % and Br 42.9%, respectively on oxidation…
Idea: Allylic and Benzylic Reactivity in SN1
Asked the year beforeHardDiagram based · figure
JEE Main 20216 questions in 6 shifts
- 3 Aug, Shift 2Q45Arrange the following halides in the increasing order of their reactivity towards reaction mechanism.
Idea: Allylic and Benzylic Reactivity in SN1
MediumSingle correct · figure - 4 Aug, Shift 2Q43Neopentyl bromide on reaction with ethyl alcohol gives, as the major product,
Idea: Neopentyl Halide Exceptions
New ideaMediumOther · figure - 26 Aug, Shift 1Q44Among the following compounds I-IV, which one forms a yellow precipitate on reacting sequentially with (i) NaOH (ii) dil. …
Idea: Reactivity of Allylic and Benzylic Halides
New ideaMediumDiagram based · figure - 31 Aug, Shift 1Q45The correct order of reactivity of the given chlorides with acetate in acetic acid is :
Idea: Allylic and Benzylic Reactivity in SN1
HardDiagram based · figure - 17 Mar, Shift 2Q43The correct pair(s) of the ambident nucleophiles is (are) : (A) (B) (C)…
Idea: Ambident Nucleophiles (Cyanide/Nitrite)
New ideaMediumOther - 18 Mar, Shift 2Q42Given below are two statements : Statement I : and AgCN both can generate nucleophile. Statement II : KCN and AgCN…
Idea: Ambident Nucleophiles (Cyanide/Nitrite)
New ideaMediumTwo statements
JEE Main 20206 questions in 5 shifts
- 2 Sep, Shift 2 · Q42Rate Law and Concentration DependenceNew ideaMedium
- 3 Sep, Shift 1 · Q44SN1 Carbocation IntermediateNew ideaMedium
- 3 Sep, Shift 2 · Q42Allylic and Benzylic Reactivity in SN2New ideaHard
- 3 Sep, Shift 2 · Q45Temperature Effects on Substitution vs EliminationNew ideaMedium
- 4 Sep, Shift 1 · Q41Substrate Steric EffectsNew ideaHard
- 4 Sep, Shift 2 · Q40Neighboring Group Participation (NGP)New ideaHard
JEE Main 20171 question in 1 shift
Questions from the official JEE Main Paper 1 shifts published by NTA (CBSE for 2017). Questions NTA dropped are left out. Topic and idea tags, counts and notes are Lumi’s.