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JEE Main 202227 JuneEvening Shift
Exam
JEE Main
Year
2022
Date
27 June
Shift
Evening Shift
Subject
Chemistry
Chapter
General Principles and Processes of Isolation of Metals

JEE Main 2022 · 27 June · Evening Shift · Chemistry · General Principles and Processes of Isolation of Metals

Statement I: Leaching of gold with cyanide ion in absence of air /...

Statement I: Leaching of gold with cyanide ion in absence of air / O2{O}_{2} leads to cyano complex of AuAu(III).

Statement II: Zinc is oxidized during the displacement reaction carried out for gold extraction.

In the light of the above statements, choose the correct answer from the options given below.

Options

  1. ABoth Statement 1 and statement 2 are correct
  2. BBoth Statement 1 and statement 2 are incorrect
  3. CStatement 1 is correct but statement 2 is incorrect
  4. DStatement 1 is incorrect but statement 2 is correct

Correct answer

D. Statement 1 is incorrect but statement 2 is correct

Step-by-step solution

4Au(s)+8CN−(aq)+2H2O(aq)+O2(g)→4[Au(CN)2]−(aq)+4OH−(aq)4Au\left(s\right) + 8{CN}^{-}\left(aq\right) + 2{H}_{2}O\left(aq\right) + {O}_{2}\left(g\right) \to 4{\left[Au{\left(CN\right)}_{2}\right]}^{-}\left(aq\right) + 4{OH}^{-}\left(aq\right)

The oxidation state of gold in the complex is +1.

2[Au(CN)2]−(aq)+Zn(s)→2Au(s)+[Zn(CN)4]2−(aq)2{\left[Au{\left(CN\right)}_{2}\right]}^{-}\left(aq\right) + Zn\left(s\right) \to 2Au\left(s\right) + {\left[Zn{\left(CN\right)}_{4}\right]}^{2 -}\left(aq\right)

The oxidation state of zinc in the complex is +2.

Oxidation state of Zn in [Zn(CN)4]2−{\left[Zn{\left(CN\right)}_{4}\right]}^{2 -} +2.

As, Oxidation state of zinc is converted from zero(elemental state) to +2.It is undergoing oxidation.

Hence,Statement 1 is incorrect but statement 2 is correct

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