General Principles and Processes of Isolation of Metals — JEE Advanced · 2023 · 04 Jun 2023 · Paper 1 Question with Solution

The correct statement(s) related to processes involved in the extraction of metals is(are)
(A) Roasting of Malachite produces Cuprite.
(B) Calcination of Calamine produces Zincite.
(C) Copper pyrites is heated with silica in a reverberatory furnace to remove iron.
(D) Impure silver is treated with aqueous KCN in the presence of oxygen followed by reduction with zinc metal.

(A)Roasting of Malachite produces Cuprite.
(B)Calcination of Calamine produces Zincite.✓ Correct
(C)Copper pyrites is heated with silica in a reverberatory furnace to remove iron.✓ Correct
(D)Impure silver is treated with aqueous KCN in the presence of oxygen followed by reduction with zinc metal.✓ Correct

Answer: (B), (C), (D)

Solution

Roasting of Malachite (A): Under roasting conditions, malachite (

CuCO X_{3} \cdot Cu (OH) X_{2}

) decomposes to copper(II) oxide (CuO), not cuprite (

Cu X_{2} O

). So (A) is incorrect.

Calcination of Calamine (B):

ZnCO X_{3} ZnO + CO X_{2}

. Calamine (zinc carbonate) produces zincite (zinc oxide) on calcination. Correct.

Copper pyrites with silica (C): Copper pyrites is heated in a reverberatory furnace with silica. Iron oxide forms iron silicate slag (

FeO + SiO X_{2} FeSiO X_{3}

), removing iron. Correct.

Silver extraction (D): Impure silver is treated with aqueous KCN in the presence of oxygen to form

[Ag (CN) X_{2}] X^{-}

, which is then reduced with zinc metal to obtain pure silver. Correct.

Answer: (B), (C), (D)

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JEE Advanced · 2023 · 04 Jun 2023 · Paper 1 · General Principles and Processes of Isolation of Metals

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