Formation of metallic copper from the sulphide ore in the normal thermo-metallurgical process essentially involves which one of the following reactions?

The byproduct in the extraction of iron is

Which of the following reactions takes place during the smelting process?

Given below are two statements.
Statement $I$: According to the Ellingham diagram,any metal oxide with higher $\Delta G^{\circ}$ is more stable than the one with lower $\Delta G^{\circ}$.
Statement $II$: The metal involved in the formation of oxide placed lower in the Ellingham diagram can reduce the oxide of a metal placed higher in the diagram.
In the light of the above statements,choose the correct answer from the options given below.

The Ellingham diagram for zinc,magnesium,and carbon converting into corresponding oxides is shown below. To make the following reduction process spontaneous,the temperature should be:
$ZnO + C \to Zn + CO$

Smelting is carried out in a ...... .