JEE Advanced 2023 · Paper 1, Chemistry question 1

(A) False. Roasting malachite, $\ce{CuCO3.Cu(OH)2}$, gives $\ce{CuO}$, not cuprite ($\ce{Cu2O}$).

(B) True. Calcining calamine gives zincite: $\ce{ZnCO3 -> ZnO + CO2}$.

(C) True. Iron in copper pyrites ends up as FeO, which silica removes as slag in the reverberatory furnace: $\ce{FeO + SiO2 -> FeSiO3}$.

(D) True. This is the cyanide process for silver:

• $\ce{4Ag + 8CN- + 2H2O + O2 -> 4[Ag(CN)2]- + 4OH-}$;
• then zinc displaces the silver: $\ce{2[Ag(CN)2]- + Zn -> [Zn(CN)4]^2- + 2Ag}$.