JEE Advanced 2021 · Paper 1 · Chemistry Q15

ChemistryMultiple correct+4 / -2Question 34 of 57

The correct statement(s) related to the metal extraction processes is(are)

A mixture of PbS and PbO undergoes self-reduction to produce Pb and

\ce{SO2}

In the extraction process of copper from copper pyrites, silica is added to produce copper silicate.

Partial oxidation of sulphide ore of copper by roasting, followed by self-reduction produces blister copper.

In cyanide process, zinc powder is utilized to precipitate gold from

\ce{Na[Au(CN)2]}

Answer and worked solution

Official answer: A, C, D

Check each option.

(A) Self-reduction of lead: $\ce{PbS + 2PbO -> 3Pb + SO2}$ . True.
(B) Silica removes iron as $\ce{FeSiO3}$ slag, not as copper silicate. False.
(C) $\ce{Cu2S}$ is partly roasted to $\ce{Cu2O}$ , then $\ce{Cu2S + 2Cu2O -> 6Cu + SO2}$ gives blister copper. True.
(D) In the cyanide process, $\ce{2Na[Au(CN)2] + Zn -> Na2[Zn(CN)4] + 2Au}$ . True.

(A), (C), (D)

Topics:Extraction of specific metals

JEE Advanced 2021 · Paper 1, Chemistry question 15