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Saturday, 31 October

JEE Main 2022 · ChemistryMultiple choiceSingle correctEasyConceptual

JEE Main 25 June 2022, Shift 1, Chemistry Q64

Question 64 of 90 in this shift, Chemistry question 4 of 30, Section A.

Leaching of gold with dilute aqueous solution of NaCN in presence of oxygen gives complex [A], which on reaction with zinc forms the elemental gold and another complex [B]. [A] and [B], respectively are :
  1. (1)[Au(CN)4]−[\mathrm{Au(CN)_4}]^- and [Zn(CN)2(OH)2]2−[\mathrm{Zn(CN)_2(OH)_2}]^{2-}
  2. (2)[Au(CN)2]−[\mathrm{Au(CN)_2}]^- and [Zn(OH)4]2−[\mathrm{Zn(OH)_4}]^{2-}
  3. (3)[Au(CN)2]−[\mathrm{Au(CN)_2}]^- and [Zn(CN)4]2−[\mathrm{Zn(CN)_4}]^{2-}Official answer
  4. (4)[Au(CN)4]2−[\mathrm{Au(CN)_4}]^{2-} and [Zn(CN)6]4−[\mathrm{Zn(CN)_6}]^{4-}

Official answer

Option 3

NTA final key.

Chapter
General Principles and Processes of Isolation of Elements
Topic
Metallurgical Extraction
Idea tested
MacArthur-Forrest Cyanide Process

Same idea in other shifts

Asked 6× in all
  1. 30 Jul 2022, Shift 2 · Q36Match List I with List II List I | List II A. Cyanide Process | I. Vapour phase refining B. Froth flotation process | II. Aluminium C.…EasyMatch the list
  2. 27 Jun 2022, Shift 1 · Q66Match List - I with List - II. List - I (A) Concentration of gold ore (B) Leaching of alumina (C) Froth stabiliser (D) Blister copper List…MediumMatch the list
  3. 27 Jun 2022, Shift 2 · Q63**Statement I:** Leaching of gold with cyanide ion in absence of air / O2\mathrm{O_2} leads to cyano complex of Au(III). **Statement II:**…MediumTwo statements
  4. 29 Jun 2022, Shift 1 · Q67In isolation of which one of the following metals from their ores, the use of cyanide salt is not commonly involved ?MediumSingle correct
  5. 25 Jul 2021, Shift 2 · Q35Match List I with List II : (Both having metallurgical terms) List - I (a) Concentration of Ag ore (b) Blast furnace (c) Blister copper…EasyMatch the list

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.