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Saturday, 31 October

JEE Main 2020 · ChemistryMultiple choiceOtherMediumApplication

JEE Main 3 September 2020, Shift 1, Chemistry Q45

Question 45 of 75 in this shift, Chemistry question 20 of 25.

The Kjeldahl method of Nitrogen estimation fails for which of the following reaction products ? (a) [figure: a six-membered ring drawn with three inner double-bond lines, bearing a substituent labelled NO2\mathrm{NO_2} on a vertical line at the top; arrow labelled Sn/HCl\mathrm{Sn/HCl}; no product drawn] (b) [figure: the same kind of ring bearing a substituent labelled CN at the top; arrow labelled LiAlH4\mathrm{LiAlH_4}; no product drawn] (c) [figure: the same kind of ring bearing a substituent labelled CH2CN\mathrm{CH_2CN} at the top; arrow labelled (i) SnCl2+HCl\mathrm{SnCl_2+HCl} (ii) H2O\mathrm{H_2O}; no product drawn] (d) [figure: the same kind of ring bearing a substituent labelled NH2\mathrm{NH_2} at the upper right; arrow labelled NaNO2\mathrm{NaNO_2} above and HCl below; no product drawn]

The figure, in words

Four drawn reactant structures (a)-(d), each a six-membered ring with three inner double-bond lines and one labelled substituent, followed by a reaction arrow with reagents; no products are drawn. Described in the stem.
  1. (1)(a) and (d)
  2. (2)(c) and (d)Official answer
  3. (3)(b) and (c)
  4. (4)(a), (c) and (d)

Official answer

Option 2

NTA final key (Sep 2020).

Chapter
Organic Chemistry: Some Basic Principles and Techniques
Topic
Stoichiometry
Idea tested
Stoichiometry of Kjeldahl Method

Same idea in other shifts

Asked 9× in all
  1. 1 Feb 2024, Shift 1 · Q71In Kjeldahl's method for estimation of nitrogen, CuSO4\mathrm{CuSO_4} acts as :EasySingle correct
  2. 1 Feb 2024, Shift 2 · Q87Following Kjeldahl's method, 1g of organic compound released ammonia, that neutralised 10 mL of 2M H2SO4\mathrm{H_2SO_4}. The percentage of…EasyNumerical value
  3. 25 Jul 2022, Shift 1 · Q88While estimating the nitrogen present in an organic compound by Kjeldahl's method, the ammonia evolved from 0.250.25 g of the compound…EasyNumerical value
  4. 24 Jun 2022, Shift 1 · Q88A 0.166 g sample of an organic compound was digested with conc. H2SO4\mathrm{H_2SO_4} and then distilled with NaOH. The ammonia gas evolved…MediumNumerical value
  5. 29 Jun 2022, Shift 1 · Q88Kjeldahl's method was used for the estimation of nitrogen in an organic compound. The ammonia evolved from 0.55 g of the compound…EasyNumerical value
  6. 25 Jul 2021, Shift 2 · Q590.8 g of an organic compound was analysed by Kjeldahl's method for the estimation of nitrogen. If the percentage of nitrogen in the…MediumNumerical value
  7. 17 Mar 2021, Shift 2 · Q42Nitrogen can be estimated by Kjeldahl's method for which of the following compound ?MediumDiagram basedHas a figure
  8. 8 Jan 2020, Shift 2 · Q40Kjeldahl's method cannot be used to estimate nitrogen for which of the following compounds ?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.