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Saturday, 31 October

JEE Main 2024 · ChemistryNumerical answerNumerical valueMediumDiagram reading

JEE Main 8 April 2024, Shift 2, Chemistry Q89

Question 89 of 90 in this shift, Chemistry question 29 of 30, Section B.

Total number of optically active compounds from the following is ___________. (1) Fischer projection: CH3\mathrm{CH_3} on top; H-C-OH; H-C-OH; CH3\mathrm{CH_3} at bottom (H and OH drawn on the left and right respectively at both carbons) (2) zigzag skeletal chain with OH groups on three consecutive carbons (two OH drawn up, middle OH drawn down) (3) CH3−CH2−CH2−CH2−OH\mathrm{CH_3-CH_2-CH_2-CH_2-OH}, CH3−CH2−CH(Cl)−CH3\mathrm{CH_3-CH_2-CH(Cl)-CH_3}, CH3−CH2−CH2−CH2−Cl\mathrm{CH_3-CH_2-CH_2-CH_2-Cl}, (CH3)2CH−CH2−CH2−Cl\mathrm{(CH_3)_2CH-CH_2-CH_2-Cl}

The figure, in words

Compounds: Fischer projection of 2,3-butanediol (CH3 top and bottom, H on left and OH on right at both middle carbons); a zigzag skeletal triol with OH on the 3rd, 4th, 5th carbons of a seven-carbon chain (outer two OH up, middle OH down); and the four listed condensed formulas.

Official answer

1

NTA final key.

Chapter
Haloalkanes and Haloarenes
Topic
Stereoisomerism
Idea tested
Chiral Centers

Same idea in other shifts

Asked 12× in all
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  2. 1 Feb 2024, Shift 1 · Q89Number of optical isomers possible for 2-chlorobutane ________.EasyNumerical value
  3. 11 Apr 2023, Shift 2 · Q79Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R. Assertion A : A solution of the…MediumAssertion–reason
  4. 29 Jul 2022, Shift 2 · Q75Given below are two statements. Statement I: The compound [figure: compound (A), a drawn structure with a stereocentre bearing…MediumTwo statementsHas a figure
  5. 29 Jun 2022, Shift 1 · Q89Observe structures of the following compounds [figure: five structures] The total number of structures/compounds which possess asymmetric…EasyNumerical valueHas a figure
  6. 29 Jun 2022, Shift 2 · Q88The number of chiral alcohol(s) with molecular formula C4H10O\mathrm{C_4H_{10}O} is _____.MediumNumerical value
  7. 8 Jan 2020, Shift 1 · Q50The number of chiral centres in penicillin is ______.MediumNumerical value
  8. 2 Sep 2020, Shift 1 · Q50The number of chiral carbons present in the molecule given below is ______.MediumNumerical valueHas 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.