The methods NOT involved in concentration of ore are
A. Liquation
B. Leaching
C. Electrolysis
D. Hydraulic washing
E. Froth floatation
Choose the correct answer from the options given below :

Solution

Chemistry ma’am · 3 steps

Sort each method by when it is used: concentration comes before reduction, refining comes after it.

1. Concentration. Concentration removes earthy impurities (gangue) from the ore before any metal is extracted. It works on the ore, not on the metal.
2. Refining. Refining purifies the crude metal you get after reduction. A method that works on molten or impure metal belongs here, not in concentration.

   Method	What it does	Stage
   A. Liquation	A low-melting metal such as Sn or Pb melts and flows away from its impurities	Refining
   B. Leaching	A solvent dissolves the ore and leaves gangue behind, as in the Bayer process for bauxite	Concentration
   C. Electrolysis	Electrolytic refining of impure metal, or electrolytic reduction (Al)	Refining or reduction
   D. Hydraulic washing	Running water carries away the lighter gangue from the heavier ore	Concentration
   E. Froth floatation	Sulphide ore particles stick to oil froth, gangue gets wetted and sinks	Concentration

3. So. Only liquation (A) and electrolysis (C) are not used for concentration, so the answer is (a).

The idea to keep. Ask whether the method acts on the ore or on the metal. Ore stage: hydraulic washing, magnetic separation, froth floatation, leaching. Metal stage: liquation, distillation, electrolysis, zone refining.

Answer from the NTA final answer key. Solution by PrepWiser.