$(I)$ $FeCr_2O_4+NaOH +$ air $\rightarrow (A)+Fe_2O_3$

$(II)$ $(A)+(B) \rightarrow Na_2Cr_2O_7$

Compounds $(A)$ and $(B)$ are :

$(I)$ $FeCr_2O_4+NaOH +$ air $\rightarrow Na_2CrO_4+Fe_2O_3$

$(II)$ $Na_2CrO_4 + H_2SO_4 \rightarrow Na_2Cr_2O_7$

$Na_2CrO_4$ and $Fe_2O_3$ are separated by

Which process of reduction of mineral to the metal is suited for the extraction of copper from its ores with low copper content

Incorrect match is

Select the correct option?
(Process used during metal extraction from their ore )