which of the following statements about the advantage of roasting of sulphide ore before reduction are true?I. ΔGf∘ is negative for roasting sulphide ore to oxide.II. ΔGf∘ of the sulphide ore is greater than H2S and CS2 .III. Carbon and hydrogen are suitable reducing agents for metal sulphides.IV. Roasting of the sulphide to oxide is thermodynamically feasible.     Choose the option with all true statements.