Which of the following fluxes is used to remove acidic impurities during metallurgy?

Which of the following is used to prepare medical instruments?

Which of the following is incorrect on the basis of the Ellingham diagram for carbon?

During the extraction of $Fe$,which reaction is performed in the combustion zone?

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

In the extraction of $Ca$ by electro-reduction of molten $CaCl_{2}$, some $CaF_{2}$ is added to the electrolyte for the following reason: