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Saturday, 31 October

JEE Main 2020 · ChemistryMultiple choiceSingle correctMediumMulti-step

JEE Main 3 September 2020, Shift 1, Chemistry Q43

Question 43 of 75 in this shift, Chemistry question 18 of 25.

An organic compound [A], molecular formula C10H20O2\mathrm{C_{10}H_{20}O_2} was hydrolyzed with dilute sulphuric acid to give a carboxylic acid [B] and an alcohol [C]. Oxidation of [C] with CrO3−H2SO4\mathrm{CrO_3-H_2SO_4} produced [B]. Which of the following structures are not possible for [A] ?

The figure, in words

Options 2 and 3 are printed structural formulas with CH3 branches drawn vertically above/below the main chain as stated in the option text.
  1. (1)CH3CH2CH2COOCH2CH2CH2CH3\mathrm{CH_3CH_2CH_2COOCH_2CH_2CH_2CH_3}
  2. (2)CH3−CH2−CH−COOCH2−CH−CH2CH3\mathrm{CH_3-CH_2-CH-COOCH_2-CH-CH_2CH_3} with a CH3\mathrm{CH_3} attached by a vertical bond below the first CH and a CH3\mathrm{CH_3} attached by a vertical bond above the second CH
  3. (3)CH3−CH2−CH−OCOCH2CH−CH2CH3\mathrm{CH_3-CH_2-CH-OCOCH_2CH-CH_2CH_3} with a CH3\mathrm{CH_3} attached by a vertical bond below the first CH and a CH3\mathrm{CH_3} attached by a vertical bond above the second CHOfficial answer
  4. (4)(CH3)3−C−COOCH2C(CH3)3\mathrm{(CH_3)_3-C-COOCH_2C(CH_3)_3}

Official answer

Option 3

NTA final key (Sep 2020).

Chapter
Aldehydes, Ketones and Carboxylic Acids
Topic
Carboxylic Acids and Derivatives
Idea tested
Fischer Esterification

Same idea in other shifts

Asked 3× in all
  1. 8 Apr 2025, Shift 2 · Q69A→(ii) H3O+(i) NaOHB→(ii) H2SO4,Δ(i) EtOHCA \xrightarrow[\text{(ii) H}_3\text{O}^+]{\text{(i) NaOH}} B \xrightarrow[\text{(ii) H}_2\text{SO}_4, \Delta]{\text{(i) EtOH}} C 'A'…MediumSingle correctHas a figure
  2. 29 Jun 2022, Shift 1 · Q75Given below are two statements : Statement I : The esterification of carboxylic acid with an alcohol is a nucleophilic acyl substitution.…MediumTwo statements

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.