Which furnace is used to extract iron metal from its ore?

$(i)$ Given below are the steps for the extraction of copper from its ore. Write the reactions involved:
$(a)$ Roasting of copper $(I)$ sulphide
$(b)$ Reduction of copper $(I)$ oxide with copper $(I)$ sulphide
$(c)$ Electrolytic refining
$(ii)$ Draw a neat and well-labelled diagram for the electrolytic refining of copper.

Differentiate between roasting and calcination and give examples.

What is the process of extracting a metal from its ore and obtaining it in a pure form called?

What is the molecular formula of cryolite?

What change occurs in the concentrated ore during the roasting process?