In the extraction of $Zn$,which gas is burnt in the jackets surrounding the retorts?

$CN^{-}$ solution is used in the extraction of which metal?

In a blast furnace,the highest temperature is in the:

Which of the following is used to remove silicon dioxide in the Serpeck's process for the purification of bauxite?

The cyanide process of gold extraction involves leaching out gold from its ore with $CN^{-}$ in the presence of $Q$ in water to form $R$. Subsequently,$R$ is treated with $T$ to obtain $Au$ and $Z$. Choose the correct option$(s)$.
$1$. $T$ is $Zn$
$2$. $R$ is $[Au(CN)_2]^-$
$3$. $Z$ is $[Zn(CN)_4]^{2-}$
$4$. $Q$ is $O_2$

In which metallurgical process is the metal obtained in the molten state?