Statement-1: Silica is added as a flux in reverberatory furnace, in the extraction of copper from copper pyrites.

Statement-2: Silica decreases the melting point of the ore and increases the conductivity.

Sand and ferrous oxide mix to create a fusible slag. Ferrous oxide and cuprous sulfide are created when cuprous oxide reacts with ferrous sulfide. Iron and oxygen have a stronger attraction for one another than copper does.

$\mathrm{FeO}+{\mathrm{SiO}}_2\to {\mathrm{FeSiO}}_3$

Copper pyrite changes during roasting into a combination of,

$\mathrm{FeS}+{\mathrm{Cu}}_2\mathrm{S}\to \mathrm{FeO}+{\mathrm{Cu}}_2\mathrm{O}$

Hence, option C is correct.