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Saturday, 31 October

JEE Main 2021 · ChemistryMultiple choiceDiagram basedMediumApplication

JEE Main 26 August 2021, Shift 2, Chemistry Q46

Question 46 of 90 in this shift, Chemistry question 16 of 30, Section A.

[reaction scheme] drawn structure (a skeletal chain with a branch, ending in a C=O group with H) --“X”, HCN, H2O\mathrm{H_2O}--> drawn structure (same chain; the carbon bears OH above, CN to the right and H below) --LiAlH4\mathrm{LiAlH_4}, H3O+\mathrm{H_3O^+}--> “Y” (Major Product) Consider the given reaction, Identify ‘X’ and ‘Y’ :

The figure, in words

Starting material: skeletal line drawing, a carbon chain with a one-carbon branch pointing down, ending in C=O (O above) and H at the right end. Intermediate: the end carbon with OH above, CN on a horizontal bond to the right, H below. Option structures differ in how OH, H and NH2 are attached to the end carbon (see option texts).
  1. (1)X - NaOH ; Y - [figure: same skeletal chain; the end carbon bears OH above, NH2\mathrm{NH_2} on a horizontal bond to the right and H on a short bond below right]
  2. (2)X - HNO3\mathrm{HNO_3} ; Y - [figure: same skeletal chain; the end carbon bears OH above on a vertical bond, H on a short bond below right, and a bond going right then down to NH2\mathrm{NH_2}]
  3. (3)X - NaOH ; Y - [figure: same skeletal chain; the end carbon bears OH on a diagonal bond up-right, H on a short bond below right, and a bond going right then down to NH2\mathrm{NH_2}]Official answer
  4. (4)X - HNO3\mathrm{HNO_3} ; Y - [figure: same skeletal chain; the end carbon bears OH above, NH2\mathrm{NH_2} on a horizontal bond to the right and H below on a vertical bond]

Official answer

Option 3

NTA final key.

Chapter
Aldehydes, Ketones and Carboxylic Acids
Topic
Nucleophilic Addition
Idea tested
Reduction of Cyanohydrins

Same idea in other shifts

Asked 2× in all
  1. 31 Aug 2021, Shift 1 · Q48The major products A and B in the following set of reactions are :MediumDiagram basedHas 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.