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Saturday, 31 October

JEE Main 2021 · ChemistryMultiple choiceDiagram basedMediumApplication

JEE Main 24 February 2021, Shift 1, Chemistry Q43

Question 43 of 90 in this shift, Chemistry question 13 of 30, Section A.

The product formed in the first step of the reaction of [figure] with excess Mg/Et2O(Et=C2H5)\mathrm{Mg/Et_2O(Et=C_2H_5)} is :

The figure, in words

Stem structure: chain CH3—CH2—CH—CH2—CH—CH3 with Br drawn above the first CH and Br drawn below the second CH.
  1. (1)[figure: two rows joined by two vertical bonds. Top row: CH3—CH2—CH—CH2—CH—CH3. Bottom row: CH3—CH—CH2—CH—CH2—CH3. Each of the two CH carbons of the top row is joined by a vertical bond to a CH carbon of the bottom row]
  2. (2)[figure: CH3—CH bonded to a three-membered ring, the other two ring atoms being CH2 and CH—CH3]
  3. (3)[figure: two rows joined by two vertical bonds. Top row: CH3—CH2—CH—CH2—CH—CH3. Bottom row: CH3—CH2—CH—CH2—CH—CH3. Each of the two CH carbons of the top row is joined by a vertical bond to the CH carbon below it]
  4. (4)CH3CH2\mathrm{CH_3CH_2}—CH(MgBr)—CH2\mathrm{CH_2}—CH(MgBr)—CH3\mathrm{CH_3} [figure: MgBr drawn above the first CH and below the second CH]Official answer

Official answer

Option 4

NTA final key.

Chapter
Haloalkanes and Haloarenes
Topic
No close match in our taxonomy
Idea tested
No close match in our taxonomy

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.