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NEET2017ChemistryGeneral Principles and Processes of Isolation of MetalsActual

Extraction of gold and silver involves leaching with C N - ion. Silver or gold is later recovered by:

Options

  1. ALiquation
  2. BDistillation
  3. CZone refining
  4. DDisplacement with Zn

Correct answer

D. Displacement with Zn

Step-by-step solution

Zinc metal can displace Ag and Au as Zn being more reactive than Ag and Au. The following reactions are involved in the extraction of gold or silver from their native ores. From Native ore, 4 Ag + 8 NaCN + 2 H 2 O + O 2 → Leaching 4 Na Ag CN 2 +    4 NaOH Soluble Sodium dicyanoargentate (I) 2 Na Ag CN 2 + Zn → Displacement Na 2 Zn CN 4 + 2 Ag ↓

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