Which of the following statements, about the advantage of roasting of sulphide ore before reduction is not true gt

Which of the following statements, about the advantage of roasting of

1.	Which of the following statements, about the advantage of roasting of sulphide ore before reduction is not true gt
Answer» The `DeltaG_(f)^(@)` of the sulphide is greater than those for `CS_(2)` and `H_(2)S` The `DeltaG_(F)^(@)` is negative for roasting of sulphide ore to oxide. Roasting of the sulphide to the oxide is thermodynamically feasible. Carbon and HYDROGEN are suitable reducing agents for METAL sulphides. Solution :The standard free energies of FORMATION `(DeltaG_(f)^(@))` of most of the sulphides are more negative than those of `CS_(2)` and `H_(2)S`. Hence, neither carbon nor hydrogen can reduce metal sulphides to metal. The standard free energies of formation of OXIDES are much LOWER than those of `SO_(2)` . Therefore , oxidation of metal sulphides to metal oxides is thermodynamically favourable. Hence sulphide ore is roasted to the oxide before reduction.