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Saturday, 31 October

JEE Main 2022 · ChemistryMultiple choiceSingle correctMediumApplication

JEE Main 28 July 2022, Shift 1, Chemistry Q73

Question 73 of 90 in this shift, Chemistry question 13 of 30, Section A.

Choose the correct option for the following reactions. (CH3)3C−CH=CH2\mathrm{(CH_3)_3C-CH=CH_2} (3,3-dimethylbut-1-ene, drawn as H3C−C(CH3)(CH3)−CH=CH2\mathrm{H_3C-C(CH_3)(CH_3)-CH=CH_2}) →Hg(OAc)2, H2O / NaBH4\xrightarrow{\mathrm{Hg(OAc)_2,\ H_2O\ /\ NaBH_4}} A and the same alkene →(BH3)2 / H2O2, OH⊖\xrightarrow{\mathrm{(BH_3)_2\ /\ H_2O_2,\ OH^{\ominus}}} B

The figure, in words

Alkene H3C-C(CH3)2-CH=CH2 with two reaction arrows: right Hg(OAc)2, H2O / NaBH4 giving A; left (BH3)2 / H2O2, OH- giving B.
  1. (1)'A' and 'B' are both Markovnikov addition products.
  2. (2)'A' is Markovnikov product and 'B' is anti-Markovnikov product.Official answer
  3. (3)'A' and 'B' are both anti-Markovnikov products.
  4. (4)'B' is Markovnikov and 'A' is anti-Markovnikov product.

Official answer

Option 2

NTA final key (2022 Session 2).

Chapter
Hydrocarbons
Topic
Alkenes and Alkynes
Idea tested
Oxymercuration-Demercuration

Same idea in other shifts

Asked 2× in all
  1. 26 Jun 2022, Shift 2 · Q73The major product in the following reaction [drawn skeletal structure with a double bond at the end of the chain] --(i)…MediumSingle correctHas a figure

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.