Learn

Saturday, 10 October

JEE Main 2024 · ChemistryMultiple choiceSingle correctMediumMulti-step

JEE Main 9 April 2024, Shift 2, Chemistry Q78

Question 78 of 90 in this shift, Chemistry question 18 of 30, Section A.

Which of the following compound can give positive iodoform test when treated with aqueous KOH solution followed by potassium hypoiodite.

The figure, in words

Options are condensed structural formulas: pentan-3-one, 1,2-epoxybutane (epoxide drawn with O bridging CH-CH2), 2,2-dichlorobutane, butanal.
  1. (1)CH3CH2−C(=O)−CH2CH3\mathrm{CH_3CH_2-C(=O)-CH_2CH_3}
  2. (2)CH3CH2−CH−CH2\mathrm{CH_3CH_2-CH-CH_2} with an oxygen bridging the two CH carbons (epoxide, 1,2-epoxybutane)
  3. (3)CH3CH2−CCl2−CH3\mathrm{CH_3CH_2-CCl_2-CH_3}Official answer
  4. (4)CH3CH2CH2CHO\mathrm{CH_3CH_2CH_2CHO}

Official answer

Option 3

NTA final key.

Chapter
Aldehydes, Ketones and Carboxylic Acids
Topic
Alcohols and Phenols
Idea tested
Iodoform Test for Specific Alcohols

Same idea in other shifts

Asked 4× in all
  1. 3 Apr 2025, Shift 1 · Q68Number of molecules from below which cannot give iodoform reaction is: Ethanol, Isopropyl alcohol, Bromoacetone, 2−-Butanol,…MediumSingle correct
  2. 4 Apr 2025, Shift 2 · Q67Which among the following compounds give yellow solid when reacted with NaOI/NaOH ? (A) CH3−CH(OH)−C2H5\mathrm{CH_3-CH(OH)-C_2H_5} (B)…EasyOther
  3. 29 Jun 2022, Shift 1 · Q90C6H12O6→ZymaseA→ΔNaOIB+CHI3\mathrm{C_6H_{12}O_6 \xrightarrow{Zymase} A \xrightarrow[\Delta]{NaOI} B + CHI_3} The number of carbon atoms present in the product B is…EasyNumerical value

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.