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JEE Advanced levelOne or more correct optionsDifficulty 3 of 3mt048

Select the correct statement(s) about silver recovery and copper refining.

  1. AIn the Parkes process the zinc-silver alloy sinks below the lead layer because it is denser than lead
  2. BIn the electrolytic refining of copper, zinc ions in solution are deposited at the cathode together with copper
  3. CIn the electrolytic refining of copper, silver and gold from the impure anode settle as anode mud
  4. DIn the Parkes process silver is much more soluble in molten zinc than in molten lead, and zinc and lead are immiscible

Answer: C, D

Zinc is less dense than lead, so the Zn-Ag crust floats on top (statement 1 false); silver preferentially dissolves in the immiscible zinc layer (true). Less electropositive Ag and Au are not oxidised at the anode and fall as anode mud (true). Zn2+ has a much more negative than Cu2+ and stays in solution, only copper being deposited (false).
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