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Saturday, 31 October

JEE Main 2022 · ChemistryNumerical answerNumerical valueMediumCalculation

JEE Main 26 July 2022, Shift 2, Chemistry Q85

Question 85 of 90 in this shift, Chemistry question 25 of 30, Section B.

20 mL of 0.02 M hypo solution is used for the titration of 10 mL of copper sulphate solution, in the presence of excess of KI using starch as an indicator. The molarity of Cu2+\mathrm{Cu^{2+}} is found to be ________ ×10−2\times 10^{-2} M. [nearest integer] Given : 2 Cu2++4 I−→Cu2I2+I2\mathrm{2\,Cu^{2+} + 4\,I^- \rightarrow Cu_2I_2 + I_2} I2+2S2O32−→2I−+S4O62−\mathrm{I_2 + 2S_2O_3^{2-} \rightarrow 2I^- + S_4O_6^{2-}}

Official answer

4

NTA final key.

Chapter
Redox Reactions
Topic
Redox Reactions
Idea tested
Iodometric Titration Reactions

Same idea in other shifts

Asked 2× in all
  1. 6 Apr 2026, Shift 2 · Q73500 mL of 0.2 M MnO4−\mathrm{MnO_4^-} solution in basic medium when mixed with 500 mL of 1.5 M KI solution, oxidises iodide ions to liberate…MediumNumerical value

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.