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Friday, 9 October

JEE Main 2024 · ChemistryMultiple choiceDiagram basedMediumApplication

JEE Main 31 January 2024, Shift 2, Chemistry Q80

Question 80 of 90 in this shift, Chemistry question 20 of 30, Section A.

The azo-dye (Y) formed in the following reactions is Sulphanilic acid + NaNO2\mathrm{NaNO_2} + CH3COOH\mathrm{CH_3COOH} →\rightarrow X. X + 1-naphthylamine →\rightarrow Y

The figure, in words

Reaction scheme: sulphanilic acid + NaNO2 + CH3COOH gives X; X + 1-naphthylamine (NH2 at position 1 of naphthalene) gives Y. Options are azo-dye structures.
  1. (1)[figure: HSO3-C6H4-N=N- attached to naphthalene, with NH2 on the same ring as the azo group, para to it]Official answer
  2. (2)[figure: HSO3-C6H4-N=N- attached to one ring of naphthalene, with NH2 on the other ring]
  3. (3)[figure: a naphthalene unit bearing two HO3S groups, joined by two N=N links to a second naphthalene unit bearing NH2]
  4. (4)[figure: HSO3-C6H4-N=N-naphthalene-N=N-C6H4-SO3H, bis-azo dye with two sulphanilic units]

Official answer

Option 1

NTA final key.

Chapter
Amines
Topic
Diazonium Salts
Idea tested
Azo Coupling Reactions

Same idea in other shifts

Asked 3× in all
  1. 2 Apr 2025, Shift 2 · Q69When a concentrated solution of sulphanilic acid and 1-naphthylamine is treated with nitrous acid (273 K) and acidified with acetic acid,…MediumSingle correct
  2. 30 Jan 2024, Shift 2 · Q79The products A and B formed in the following reaction scheme are respectively Benzene…EasyDiagram 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 42 of the 174 JEE Main shifts held from 2017 to 2026.