Which of the following compounds acts as a flux in the extraction of copper from copper pyrites?

Given below are two statements: one is labelled as Assertion $A$ and the other is labelled as Reason $R$.
Assertion $A:$ In an Ellingham diagram,the oxidation of carbon to carbon monoxide shows a negative slope with respect to temperature.
Reason $R:$ $CO$ tends to get decomposed at higher temperature.
In the light of the above statements,choose the correct answer from the options given below:

During the smelting of roasted copper ore,silica is added to remove:

In the extraction of iron from haematite,the impurity $(x)$ of the ore is removed in the form of '$y$'. What are $x$ and $y$ respectively?

Which of the following metals is not obtained by electrolysis?

Copper is extracted from copper pyrites by