In the extraction of copper from sulfide ore,copper metal is obtained by the reduction of $Cu_2O$ with which of the following?

Copper is the most noble of the first row transition metals and occurs in small deposits in several countries. Ores of copper include chalcanthite $(CuSO_4 \cdot 5H_2O)$,atacamite $(Cu_2Cl(OH)_3)$,cuprite $(Cu_2O)$,copper glance $(Cu_2S)$ and malachite $(Cu_2(OH)_2CO_3)$. However,$80\%$ of the world copper production comes from the ore of chalcopyrite $(CuFeS_2)$. The extraction of copper from chalcopyrite involves partial roasting,removal of iron and self-reduction. $1.$ Partial roasting of chalcopyrite produces: $(A)$ $Cu_2S$ and $FeO$ $(B)$ $Cu_2O$ and $FeO$ $(C)$ $CuS$ and $Fe_2O_3$ $(D)$ $Cu_2O$ and $Fe_2O_3$. $2.$ Iron is removed from chalcopyrite as: $(A)$ $FeO$ $(B)$ $FeS$ $(C)$ $Fe_2O_3$ $(D)$ $FeSiO_3$. $3.$ In self-reduction,the reducing species is: $(A)$ $S$ $(B)$ $O^{2-}$ $(C)$ $S^{2-}$ $(D)$ $SO_2$. Give the answer for questions $1, 2$ and $3$.

To prevent magnesium from oxidation in the electrolytic extraction process,which of the following is done?

Statement $I :$ Leaching of gold with cyanide ion in absence of air $/$ $O_2$ leads to cyano complex of $Au(III)$.
Statement $II :$ Zinc is oxidized during the displacement reaction carried out for gold extraction.
In the light of the above statements,choose the correct answer from the options given below.

Consider the following reactions at $1000\,^{\circ}C$:
$(I)$ $Zn_{(s)} + 1/2 O_{2(g)} \xrightarrow{\Delta} ZnO_{(s)};$ $\Delta G^o = -360\,kJ\,mol^{-1}$
$(II)$ $C_{(s)} + 1/2 O_{2(g)} \xrightarrow{\Delta} CO_{(g)};$ $\Delta G^o = -460\,kJ\,mol^{-1}$
Choose the correct statement at $1000\,^{\circ}C$.

Which of the following oxide groups cannot be reduced by carbon?