Which of the following processes is/are involved in the extraction of  $\text{Cu}$  from sulphide ores of copper containing iron sulphide.

Silica is added to combine with  $\text{FeO}$

Liq. Matte is placed in converter for carbon reduction

${\text{Cu}}_2\text{S}$  is partially converted to ${\text{Cu}}_2\text{O}$  by air blasting and then to metallic copper

$\text{FeS}$  is more readily converted to the oxide than  ${\text{Cu}}_2\text{S}$