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Saturday, 31 October

JEE Main 2020 · ChemistryMultiple choiceDiagram basedMediumConceptual

JEE Main 5 September 2020, Shift 1, Chemistry Q30

Question 30 of 75 in this shift, Chemistry question 5 of 25.

The increasing order of the acidity of the α\alpha-hydrogen of the following compounds is :

The figure, in words

Four structures labelled (A) to (D) as printed: (A) a carbon with =O and two unlabelled line ends (zig-zag, no atom labels); (B) Ph-C(=O)-CH2-C(=O)-Ph drawn as a zig-zag chain with two =O; (C) a C=O carbon with one unlabelled line end and OMe; (D) a C=O carbon with one unlabelled line end and NMe2.
  1. (1)(A) < (C) < (D) < (B)
  2. (2)(D) < (C) < (A) < (B)Official answer
  3. (3)(C) < (A) < (B) < (D)
  4. (4)(B) < (C) < (A) < (D)

Official answer

Option 2

NTA final key (Sep 2020).

Chapter
Aldehydes, Ketones and Carboxylic Acids
Topic
Organic Acidity and Basicity
Idea tested
Acidity of Alpha-Hydrogens in Carbonyls

Same idea in other shifts

Asked 2× in all
  1. 28 Jul 2022, Shift 1 · Q74Among the following marked proton of which compound shows lowest pKa\mathrm{pK_a} value ?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.