Match the conversions in Column I with the type(s) of reaction(s) given in Column II. Indicate your answer by darkening the appropriate bubbles of the 4 × 4 matrix given in the ORS.
Column I
(A)
(B)
(C)
(D)
Column II
(p) roasting
(q) calcination
(r) carbon reduction
(s) self reduction
Column I
(A)
(B)
(C)
(D)
Column II
(p) roasting
(q) calcination
(r) carbon reduction
(s) self reduction
Answer: A → I, B → II, C → I, C → III, D → I, D → IV
Solution
(A) PbS → PbO: Roasting (heating sulfide ore in excess air to convert to oxide).
(B) CaCO₃ → CaO: Calcination (heating carbonate in limited air to decompose and remove CO₂).
(C) ZnS → Zn: First roasting to convert ZnS to ZnO, then carbon reduction of ZnO to Zn.
(D) Cu₂S → Cu: Roasting converts some Cu₂S to Cu₂O, then self-reduction occurs where Cu₂S and Cu₂O react to give Cu without external reducing agent.
(B) CaCO₃ → CaO: Calcination (heating carbonate in limited air to decompose and remove CO₂).
(C) ZnS → Zn: First roasting to convert ZnS to ZnO, then carbon reduction of ZnO to Zn.
(D) Cu₂S → Cu: Roasting converts some Cu₂S to Cu₂O, then self-reduction occurs where Cu₂S and Cu₂O react to give Cu without external reducing agent.
JEE Advanced · 2008 · 13 Apr 2008 · Paper 2 · Match the columns