In the extraction of zinc,what burns to produce a blue flame?

In the metallurgy of aluminium,cryolite is mixed in the molten state because it

Which of the following metals cannot be extracted by carbon reduction process?

Matte is a mixture of .......... .

Explain electrometallurgy in detail.

The value of ${\Delta _r}{G^\Theta }$ for the formation of $Cr_2O_3$ is $-540 \, kJ \, mol^{-1}$ and that of $Al_2O_3$ is $-827 \, kJ \, mol^{-1}$. Is the reduction of $Cr_2O_3$ possible with $Al$?