$\begin{array}{1 1} \text{(a) Sulphide ore is roasted to the oxide before reduction because metal oxides can be reduced to Non - metal by carbon and hydrogen much more easily than sulphides.} \\ \text{(b) Sulphide ore is roasted to the oxide before reduction because metal oxides can be reduced to metal by carbon and hydrogen much more easily than sulphides. }\\ \text{(c)Sulphide ore is roasted to the oxide before reduction because metal oxides can be reduced to metal by Oxygen much more easily than sulphides. } \\\text{(d) Sulphide ore is roasted to the oxide before reduction because metal oxides can be reduced to metal by hydrogen much more easily than sulphides. }\end{array} $