$I$. $FeCr_2O_4 + NaOH + \text{air} \rightarrow (A) + Fe_2O_3$
$II$. $(A) + (B) \rightarrow Na_2Cr_2O_7$
$III$. $Na_2Cr_2O_7 + X \xrightarrow{\Delta} Cr_2O_3$
$IV$. $Cr_2O_3 + Y \xrightarrow{\Delta} Cr$
High temperature $(> 1000 \ ^\circ C)$ electrolytic reduction is necessary for isolating:

In the alumino-thermite process,$Al$ metal acts as

The reaction occurring in the final stage of the extraction of copper from copper pyrites in a Bessemer converter is:

The Ellingham diagram represents:

$Aluminium$ oxide is not reduced by chemical reactions since:

Given below are two statements: one is labelled as Assertion $(A)$ and the other is labelled as Reason $(R).$
Assertion $(A):$ Aluminium is extracted from bauxite by the electrolysis of a molten mixture of $Al_2O_3$ with cryolite.
Reason $(R):$ The oxidation state of $Al$ in cryolite is $+3$.
In the light of the above statements,choose the most appropriate answer from the options given below: