Refining of silver is done by :

The metal for which its property of formation of a volatile complex is taken into account for its extraction is:

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:

Which of the following employ$(s)$ thermal decomposition of volatile iodide compounds?

Describe a method for refining nickel.

Explain the purification of metals in the vapour phase with an example.