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Saturday, 31 October

JEE Main 2021 · ChemistryMultiple choiceSingle correctEasyRecall

JEE Main 26 February 2021, Shift 1, Chemistry Q50

Question 50 of 90 in this shift, Chemistry question 20 of 30, Section A.

On treating a compound with warm dil. H2SO4\mathrm{H_2SO_4}, gas X is evolved which turns K2Cr2O7\mathrm{K_2Cr_2O_7} paper acidified with dil. H2SO4\mathrm{H_2SO_4} to a green compound Y. X and Y respectively are :
  1. (1)X=SO3, Y=Cr2(SO4)3\mathrm{X{=}SO_3,\ Y{=}Cr_2(SO_4)_3}
  2. (2)X=SO2, Y=Cr2O3\mathrm{X{=}SO_2,\ Y{=}Cr_2O_3}
  3. (3)X=SO3, Y=Cr2O3\mathrm{X{=}SO_3,\ Y{=}Cr_2O_3}
  4. (4)X=SO2, Y=Cr2(SO4)3\mathrm{X{=}SO_2,\ Y{=}Cr_2(SO_4)_3}Official answer

Official answer

Option 4

NTA final key.

Chapter
Organic Chemistry: Some Basic Principles and Techniques
Topic
Anion Analysis
Idea tested
Sulfite Dichromate Paper Test

Same idea in other shifts

Asked 2× in all
  1. 5 Apr 2026, Shift 2 · Q70A paper dipped in a dil. H2SO4\mathrm{H_2SO_4} solution of 'X' upon treatment with SO2\mathrm{SO_2} gas turns into green. The compound 'X' is :EasySingle correct

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. Lumi analyses 108 of the 174 JEE Main shifts held from 2017 to 2026.