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Saturday, 31 October

JEE Main 2021 · ChemistryMultiple choiceAssertion–reasonMediumConceptual

JEE Main 18 March 2021, Shift 1, Chemistry Q36

Question 36 of 90 in this shift, Chemistry question 6 of 30, Section A.

Given below are two Statements : One is labelled as Assertion A and the other is labelled as Reason R : Assertion A : During the boiling of water having temporary hardness, Mg(HCO3)2\mathrm{Mg(HCO_3)_2} is converted to MgCO3\mathrm{MgCO_3}. Reason R : The solubility product of Mg(OH)2\mathrm{Mg(OH)_2} is greater than that of MgCO3\mathrm{MgCO_3}. In the light of the above statements, choose the most appropriate answer from the options given below :
  1. (1)Both A and R are true and R is the correct explanation of A
  2. (2)Both A and R are true but R is NOT the correct explanation of A
  3. (3)A is true but R is false
  4. (4)A is false but R is trueOfficial answer

Official answer

Option 4

NTA final key.

Chapter
Hydrogen
Topic
Hydrogen and Hydrides
Idea tested
Temporary Hardness and Clark's Method

Same idea in other shifts

Asked 3× in all
  1. 28 Jul 2022, Shift 2 · Q34The products obtained during treatment of hard water using Clark's method are :EasySingle correct
  2. 26 Jun 2022, Shift 2 · Q65Boiling of hard water is helpful in removing the temporary hardness by converting calcium hydrogen carbonate and magnesium hydrogen…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.