JEE Advanced (Single Correct MCQs): General Principles & Processes of Isolation of Elements - JEE MCQ

Malachite is CuCO₃ . Cu (OH)₂ it is ore of copper.

Al reduces Fe₂O₃ or Cr₂O₃ to respective metals and acts as a reducing agent.
Fe₂O₃ + 2Al → Al₂O₃ + 2Fe

NOTE : During the extraction of copper, iron is present in the ore as impurity (FeS).
The ore together with a little coke and silica is smelted; FeS present as impurity in the ore is oxidized to iron oxide, which then reacts with silica to form fusible ferrous silicate which is removed as slag.

Cuprite : Cu₂O; Chalcocite : Cu₂S; Chalcopyrite : CuFeS₂;
Malachite: Cu(OH)₂.CuCO₃. We see that CuFeS₂ contais both Cu and Fe.

NOTE : Extraction of Zn from ZnS (Zinc blende) is achieved by roasting followed by reduction with carbon.
2ZnS + 3O₂ → 2ZnO + 2SO₂
ZnO + C → Zn + CO

(i) Haematite is Fe₂O₃ in which Fe is present in III oxidation state.
(ii) Magnetite (Fe₄O₃) is an equimolar mixture of FeO and Fe₂O₃.
Oxidation state of Fe in FeO is II.
Oxidation state of Fe in Fe₂O₃ is III.

The reactions involved in cyanide extraction process are :

Silver, copper and lead are commonly found in earth's crust as Ag₂S (silver glance), CuFeS₂ (copper pyrites) and PbS (galena)