Which refining process is represented by the equation $Ti_{(s)} + 2I_{2(g)}$ $\xrightarrow{523 \ K} TiI_{4(g)}$ $\xrightarrow{1700 \ K} Ti_{(s)} + 2I_{2(g)}$?

In the electrolytic refining of an impure metal,a rod of impure metal is used as the anode and a rod of pure metal is used as the cathode,and the aqueous solution of its salt is electrolyzed. Which of the following metals cannot be refined by this method?

Which metal is ultrapurified using carbon monoxide?

$A$ metal which is refined by poling is

In electrorefining of copper,some gold is produced as

Formation of $Ni(CO)_4$ and its subsequent decomposition into $Ni$ and $CO$ (recycled) forms the basis of the Mond process.
$Ni + 4CO$ $\xrightarrow{T_1} Ni(CO)_4$ $\xrightarrow{T_2} Ni + 4CO$
$T_1$ and $T_2$ are: