Which following compound acts as a flux in extraction of copper from copper pyrites

Which following compound acts as a flux in extraction of copper from copper pyrites
  1. $\mathrm{CaSiO}_{3}$
  2. $\mathrm{FeO}$
  3. $\mathrm{FeSiO}_{3}$
  4. $\mathrm{SiO}_{2}$

Solution

Copper is extracted from the ore copper pyrite by smelting in a blast furnace. The flux used is $\mathrm{SiO}_{2}$ and slag formed is $\mathrm{FeSiO}_{3}$.

Asked in: MHT CET 2020 (20 Oct Shift 1)

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