Medium MCQ +4 / -1 PYQ · JEE Mains 2021

Given below are two statements : One is labelled as Assertion A and the other labelled as reason R

Assertion A : During the boiling of water having temporary hardness, Mg(HCO3)2 is converted to MgCO3.

Reason R : The solubility product of Mg(OH)2 is greater than that of MgCO3.

In the light of the above statements, choose the most appropriate answer from the options given below :

  1. A Both A and R are true but R is not the correct explanation of A
  2. B A is true but R is false
  3. C Both A and R are true and R is the correct explanation of A
  4. D A is false but R is true Correct answer

Solution

<b>A</b> : For temporary hardness,<br> Mg(HCO<sub>3</sub>)<sub>2</sub> $\buildrel {heating} \over \longrightarrow$ Mg(OH)<sub>2</sub> + 2CO<sub>2</sub> Assertion is false. MgCO<sub>3</sub> has high solubility product than Mg(OH)<sub>2</sub>.<br><br> <b>R</b> : MgCO<sub>3</sub> is more water soluble than Mg(OH)<sub>2</sub>. <br><br> K<sub>SP(Mg(OH)<sub>2</sub>)</sub> = 1.8 × 10<sup>–11</sup><br><br> K<sub>SP(MgCO<sub>3</sub>)</sub> = 3.5 × 10<sup>–8</sup>

About this question

Subject: Chemistry · Chapter: Equilibrium · Topic: Chemical Equilibrium and Kc, Kp

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