What is the process of metallurgy?

Carbon reduction process is not commercially applicable for which of the following set of oxides to extract the respective metal?
$(I)$ $ZnO$,$(II)$ $Fe_2O_3$,$(III)$ $Al_2O_3$,$(IV)$ $SnO_2$,$(V)$ $MgO$

Which of the following compounds is used for the extraction of aluminum by electrolysis?

Out of $C$ and $CO$,which is a better reducing agent at $673 \, K$?

Furnaces are lined with $CaO$ because

$Ag_2S + NaCN \to (A)$,$(A) + Zn \to (B)$
$(B)$ is a metal. Hence,$(A)$ and $(B)$ are: