Medium MCQ +4 / -1 PYQ · JEE Mains 2020

For the following Assertion and Reason, the correct option is

Assertion (A): When Cu (II) and sulphide ions are mixed, they react together extremely quickly to give a solid.

Reason (R): The equilibrium constant of
Cu2+(aq) + S2–(aq) ⇌ CuS(s) is high because the solubility product is low.

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

Solution

K<sub>sp</sub> value of CuS is very low 10<sup>–36</sup> (3.6 × 10<sup>–36</sup>) due to low K<sub>sp</sub> value Cu<sup>+2</sup> ion gets precipitated very quickly even with very low concentration of S<sup>–2</sup> ion.

About this question

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

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