State whether the following statement is true or false:
The elements or compounds,which occur naturally in the earth's crust,are known as minerals.

Give reasons: Carbonate and sulphide ores are usually converted into oxides during the process of extraction.

In the electrolytic refining of copper metal,which of the following decreases in weight?

During the electrolytic refining of zinc,it gets

$(i)$ 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.

In the $Bayer$ process,what is obtained when concentrated $NaOH$ is added to bauxite?