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Saturday, 31 October

JEE Main 2021 · ChemistryMultiple choiceSingle correctEasyRecall

JEE Main 25 July 2021, Shift 1, Chemistry Q48

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

[figure: polymer repeating unit −(CH2-(\mathrm{CH_2}-C6H3(OH)-CH2\mathrm{CH_2}-C6H3(OH)-CH2)−\mathrm{CH_2})-, phenol rings joined through CH2 groups at ortho and para positions relative to OH] is a repeating unit for :

The figure, in words

Repeating unit in large brackets: CH2 linking two phenol rings (each with OH ortho to the CH2 links), i.e. the novolac type phenol-formaldehyde chain.
  1. (1)Neoprene
  2. (2)Buna-N
  3. (3)NovolacOfficial answer
  4. (4)Acrilan

Official answer

Option 3

NTA final key.

Chapter
Polymers
Topic
Polymers
Idea tested
Novolac Structure and Role

Same idea in other shifts

Asked 3× in all
  1. 25 Jun 2022, Shift 2 · Q88The Novolac polymer has mass of 963 g. The number of monomer units present in it are ________MediumNumerical value
  2. 31 Aug 2021, Shift 1 · Q49Monomer of Novolac is :EasySingle correct

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.