Furnaces are lined with $CaO$ because

Explain the reduction of metal oxides to metal.

During the extraction of gold,the following reactions take place: $4Au + 8CN^{-} + 2H_2O + O_2 \longrightarrow 4[Au(CN)_2]^{-} + 4OH^{-}$ and $2[Au(CN)_2]^{-} + Zn \longrightarrow [Zn(CN)_4]^{2-} + 2Au$. $X$ and $Y$ are respectively:

In which of the following production processes is limestone $(CaCO_3)$ $NOT$ used?

Explain the hydrometallurgical process with a suitable example.

During the extraction of silver,which of the following is formed?