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

Explanation

Two basic requirement are
(i) Metal should form volatile compound with available reagent. ltbr. (ii) The volatile compound should be easily decomposable so that it can be recovered easily.
(a) Mond's process includes conversion of Ni to `Ni(CO)_(4)` and then decomposition of `Ni(CO)_(4)` to Ni.
`Ni+4CO to Ni(CO)_(4)`
`Ni(CO)_(4) overset(450-470K) to Ni +4CO`
(b) Van Arkel method include converstion of Zr to volatile `ZrI_(4)` and then decomposition of`ZrI_(4)` to Zr and `I_(2)`.
`Zr+2I_(2) overset(870K) to ZrI_(4) overset(2075 K) to Zr+2I_(2)`