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Saturday, 31 October

JEE Main 2021 · ChemistryMultiple choiceSingle correctEasyApplication

JEE Main 4 August 2021, Shift 1, Chemistry Q43

Question 43 of 90 in this shift, Chemistry question 13 of 30, Section A.

Select the most suitable reagent for the following reduction reaction

The figure, in words

Reaction scheme: H3C-C≡C-CH3 drawn on the left, an arrow, and on the right a drawn C=C double bond with H3C and H on the left carbon (H3C upper left, H lower left) and H and CH3 on the right carbon (H upper right, CH3 lower right).
  1. (1)H2\mathrm{H_2}, Pd/C, Quinoline
  2. (2)H2\mathrm{H_2}, Na/Liq. NH3\mathrm{NH_3}Official answer
  3. (3)LiAlH4/H3O+\mathrm{LiAlH_4/H_3O^+}
  4. (4)Pt/H2\mathrm{Pt/H_2}

Official answer

Option 2

NTA final key.

Chapter
Hydrocarbons
Topic
Alkenes and Alkynes
Idea tested
Stereoselective Alkyne Reduction

Same idea in other shifts

Asked 4× in all
  1. 4 Apr 2026, Shift 2 · Q64Compound (X) is subjected to the sequence of reactions as shown above. Molar mass of the major product (Y) formed is ________…MediumDiagram basedHas a figure
  2. 6 Apr 2024, Shift 1 · Q88The major product of the following reaction is P. CH3C=C−CH3\mathrm{CH_3C = C - CH_3}…MediumNumerical valueHas a figure
  3. 1 Feb 2024, Shift 2 · Q75In the given reactions identify A and B H2+A→Pd/C\mathrm{H_2 + A \xrightarrow{Pd/C}} [figure: alkene with CH3\mathrm{CH_3} (upper left) and…EasyOtherHas 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.