What is the composition of the anode mud in the electrolytic refining of silver?

Which method of refining nickel is represented by the following equation?
$Ni$ (impure) $+ 4CO$ $\xrightarrow{320 \ K} Ni(CO)_4$ $\xrightarrow{420 \ K} Ni$ (pure) $+ 4CO$

Choose the correct option for vapor phase refining.
$A :$ The metal should form a volatile compound with an appropriate reagent.
$R :$ The volatile compound obtained should be easily decomposable.

$Si$ and $Ge$ used for semiconductors are required to be of high purity and hence purified by:

Match the following:

List-$I$ (Process)	List-$II$ (Metal)
$A$. Hall-Heroult process	$I$. $Ti$
$B$. Mond process	$II$. $In$
$C$. van-Arkel process	$III$. $Al$
$D$. Zone refining process	$IV$. $Ni$

The correct answer is:

When the sample of copper with zinc impurity is to be purified by electrolysis,the appropriate electrodes are:
Cathode,Anode