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Saturday, 31 October

JEE Main 2021 · ChemistryMultiple choiceDiagram basedMediumMulti-step

JEE Main 26 February 2021, Shift 1, Chemistry Q42

Question 42 of 90 in this shift, Chemistry question 12 of 30, Section A.

For the given reaction : [reaction scheme, see figure_note: structure →2. Red hot iron tube, 873 K1. NaNH2\xrightarrow[\text{2. Red hot iron tube, 873 K}]{\text{1. }\mathrm{NaNH_2}} (A) (major product)] What is ‘A’ ?

The figure, in words

Stem scheme as drawn: CH=CHBr with CH3 attached by a vertical bond below the left CH; arrow labelled 1. NaNH2, 2. Red hot iron tube, 873 K; product (A) (major product). Option 1: CH=CH-NH2 with CH3 below the first CH. Option 3: hexagon with alternating double bonds, no substituents. Option 4: hexagon with alternating double bonds (no inner circle), H3C at upper-left vertex, CH3 at upper-right vertex, CH3 at bottom vertex.
  1. (1)CH=CH−NH2\mathrm{CH{=}CH{-}NH_2} with CH3\mathrm{CH_3} attached below the first CH
  2. (2)CH3CH2CH2NH2\mathrm{CH_3CH_2CH_2NH_2}
  3. (3)[figure: six-membered ring drawn with alternating double bonds, no substituents]
  4. (4)[figure: six-membered ring drawn with alternating double bonds, bearing H3C\mathrm{H_3C} on the upper-left vertex, CH3\mathrm{CH_3} on the upper-right vertex and CH3\mathrm{CH_3} on the bottom vertex]Official answer

Official answer

Option 4

NTA final key.

Chapter
Hydrocarbons
Topic
Alkenes and Alkynes
Idea tested
Cyclic Polymerization of Alkynes

Same topic in other shifts

All Alkenes and Alkynes questions
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  2. 4 Apr 2026, Shift 2 · Q64Compound (X) is subjected to the sequence of reactions as shown above. Molar mass of the major product (Y) formed is ________…MediumDiagram basedHas a figure
  3. 5 Apr 2026, Shift 1 · Q64"P" is a hydrocarbon of molecular formula:- C8H14\mathrm{C_8H_{14}}. On ozonolysis, "P" forms "Q". "Q" on treatment with alkali under reflux…HardDiagram basedHas a figure
  4. 6 Apr 2026, Shift 1 · Q66Given below are two statements: Statement I: 3-phenylpropene reacts with HBr and gives secondary alkyl bromide having a chiral carbon atom…MediumTwo statements
  5. 6 Apr 2026, Shift 2 · Q65An optically active alkyl bromide C4H9Br\mathrm{C_4H_9Br}, reacts with ethanolic KOH to form major compound [A] which reacts with bromine to…MediumSingle correct
  6. 2 Apr 2025, Shift 1 · Q66An optically active alkyl halide C4H9Br\mathrm{C_4H_9Br} [A] reacts with hot KOH dissolved in ethanol and forms alkene [B] as major product…MediumSingle correct

Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.