Refining of nickel is done by:

Blister copper is refined by stirring molten impure metal with green logs of wood because such wood liberates hydrocarbon gases (like $CH_4$). This process $X$ is called . . . . . . . . . and the metal contains impurities of $Y$ is . . . . . . . . .

Which of the following statements are correct related to metallurgy?
$A$. In electrolytic refining of copper,pure $Cu$ is used as anode.
$B$. Zone refining is based on the principle that impurities are more soluble in the melt than in the solid state of the metal.
$C$. $TiI_4$ upon heating will give pure $Ti$.
$D$. Very pure $Zr$ may be obtained by galvanisation.
$E$. In copper smelting,hot air is used to convert to $CuSO_4$.
The correct answer is

The method used for obtaining highly pure silicon,which is used as a semiconductor material,is:

When copper is purified by the electrorefining process,noble metals like $Ag$ and $Au$ are found in:

Write two basic requirements for refining of a metal by Mond's process and by Van Arkel Method.