The correct statement(s) related to the metal extraction processes is(are)
- (A)A mixture of PbS and PbO undergoes self-reduction to produce Pb and .✓ Correct
- (B)In the extraction process of copper from copper pyrites, silica is added to produce copper silicate.
- (C)Partial oxidation of sulphide ore of copper by roasting, followed by self-reduction produces blister copper.✓ Correct
- (D)In cyanide process, zinc powder is utilized to precipitate gold from ✓ Correct
Answer: (A), (C), (D)
Solution
(A) TRUE: PbS + 2PbO → 3Pb + SO₂ is a self-reduction reaction used in lead extraction.
(B) FALSE: In copper extraction from copper pyrites (CuFeS₂), silica (SiO₂) is added to remove iron impurity as iron silicate slag (FeSiO₃), NOT to produce copper silicate.
(C) TRUE: Copper pyrites ore is partially oxidized by roasting to form Cu₂S and Cu₂O. These then undergo self-reduction: Cu₂S + 2Cu₂O → 6Cu + SO₂, producing blister copper (98-99% pure copper).
(D) TRUE: In the cyanide process (MacArthur-Forrest process), gold is leached as Na[Au(CN)₂]. Zinc powder acts as a reducing agent to precipitate gold:
2Na[Au(CN)₂] + Zn → Na₂[Zn(CN)₄] + 2Au↓
(B) FALSE: In copper extraction from copper pyrites (CuFeS₂), silica (SiO₂) is added to remove iron impurity as iron silicate slag (FeSiO₃), NOT to produce copper silicate.
(C) TRUE: Copper pyrites ore is partially oxidized by roasting to form Cu₂S and Cu₂O. These then undergo self-reduction: Cu₂S + 2Cu₂O → 6Cu + SO₂, producing blister copper (98-99% pure copper).
(D) TRUE: In the cyanide process (MacArthur-Forrest process), gold is leached as Na[Au(CN)₂]. Zinc powder acts as a reducing agent to precipitate gold:
2Na[Au(CN)₂] + Zn → Na₂[Zn(CN)₄] + 2Au↓
JEE Advanced · 2021 · 03 Oct 2021 · Paper 1 · One or more correct options