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Saturday, 31 October

JEE Main 2021 · ChemistryMultiple choiceDiagram basedMediumMulti-step

JEE Main 31 August 2021, Shift 1, Chemistry Q48

Question 48 of 90 in this shift, Chemistry question 18 of 30, Section A.

The major products A and B in the following set of reactions are :

The figure, in words

Scheme drawn: central carbon with two unlabelled line stubs to the left, OH at upper right and CN at lower right; arrow to the left labelled LiAlH4 (above) / H3O+ (below) giving A; arrow to the right labelled H3O+ (above) / H2SO4 (below) giving B.
  1. (1)A = [structure as drawn: central C with two unlabelled line stubs to the left, OH upper right, CHO lower right], B = [same drawing with OH upper right and CO2H lower right]
  2. (2)A = [central C with two unlabelled line stubs to the left, OH upper right, and a bond running down-right then horizontal to NH2], B = [central C, two stubs left, OH upper right, CHO lower right]
  3. (3)A = [central C with two unlabelled line stubs to the left, OH upper right, and a bond running down-right then horizontal to OH], B = [central C, two stubs left, OH upper right, CHO lower right]
  4. (4)A = [central C with two unlabelled line stubs to the left, OH upper right, and a bond running down-right then horizontal to NH2], B = [C=C double bond drawn at upper left, single stub at lower left, joined to a central C bearing COOH on a horizontal bond to the right]Official answer

Official answer

Option 4

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. 26 Aug 2021, Shift 2 · Q46[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…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.