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Saturday, 31 October

JEE Main 2024 · ChemistryMultiple choiceDiagram basedEasyRecall

JEE Main 30 January 2024, Shift 1, Chemistry Q80

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

Following is a confirmatory test for aromatic primary amines. Identify reagent (A) and (B). [Scheme: aniline (C6H5NH2\mathrm{C_6H_5NH_2}) →(A)\xrightarrow{(A)} benzenediazonium chloride (C6H5N2+Cl−\mathrm{C_6H_5N_2^+Cl^-}) →NaOH(B)\xrightarrow[\mathrm{NaOH}]{(B)} Scarlet red dye]

The figure, in words

Scheme: aniline to benzenediazonium chloride with reagent A, then with reagent B and NaOH gives scarlet red dye. Options give A as text and B as a drawn structure (naphthol / phenol / aniline).
  1. (1)A=NaNO2+HCl, 0−5∘C\mathrm{A = NaNO_2 + HCl,\ 0-5^\circ C} ; B = [figure: 2-naphthol, OH on the beta position of naphthalene]Official answer
  2. (2)A=NaNO2+HCl, 0−5∘C\mathrm{A = NaNO_2 + HCl,\ 0-5^\circ C} ; B = [figure: 1-naphthol, OH on the alpha position of naphthalene]
  3. (3)A=HNO3/H2SO4\mathrm{A = HNO_3/H_2SO_4} ; B = [figure: phenol]
  4. (4)A=NaNO2+HCl, 0−5∘C\mathrm{A = NaNO_2 + HCl,\ 0-5^\circ C} ; B = [figure: aniline]

Official answer

Option 1

NTA final key.

Chapter
Amines
Topic
Diazonium Salts
Idea tested
Azo Coupling Reactions

Same idea in other shifts

Asked 11× 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. 6 Apr 2024, Shift 1 · Q909.3 g of pure aniline upon diazotisation followed by coupling with phenol gives an orange dye. The mass of orange dye produced (assume…MediumNumerical value
  3. 30 Jan 2024, Shift 2 · Q79The products A and B formed in the following reaction scheme are respectively Benzene…EasyDiagram basedHas a figure
  4. 31 Jan 2024, Shift 2 · Q80The azo-dye (Y) formed in the following reactions is Sulphanilic acid + NaNO2\mathrm{NaNO_2} + CH3COOH\mathrm{CH_3COOH} →\rightarrow X. X +…MediumDiagram basedHas a figure
  5. 15 Apr 2023, Shift 1 · Q77Consider the following sequence of reactions: [figure: aniline (C6H5NH2\mathrm{C_6H_5NH_2})…EasyDiagram basedHas a figure
  6. 29 Jul 2022, Shift 1 · Q77[figure: benzenediazonium chloride (benzene ring bearing N+≡NCl−\mathrm{N^{+}\equiv NCl^{-}}) + 'A' →NaOH\xrightarrow{\mathrm{NaOH}} Product…EasyDiagram basedHas a figure
  7. 3 Aug 2021, Shift 1 · Q46Sulphanilic acid on diazotisation and then reaction with N,N–dimethylaniline gives which of the following? Mark if their common name is…MediumDiagram basedHas a figure
  8. 24 Feb 2021, Shift 2 · Q42The diazonium salt of which of the following compounds will form a coloured dye on reaction with β\beta-Naphthol in NaOH ?EasySingle 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.