Zone refining process is used for which of the following?

Which of the following pairs is incorrect?
$(a)$ Goldschmidt alumino-thermite process $-$ $Cr_2O_3$
$(b)$ MacArthur-Forrest cyanide process $-$ $Fe$
$(c)$ Mond process $-$ $Ni$
$(d)$ Van Arkel process $-$ $Au$

The zone refining method is based on which principle?

The formation of $Ni(CO)_4$ and its subsequent decomposition into $Ni$ and $CO$ forms the basis of the Mond process.
$Ni + 4CO$ $\xrightarrow{T_1} Ni(CO)_4$ $\xrightarrow{T_2} Ni + 4CO$
What are the values of $T_1$ and $T_2$?

The Van-Arkel method of refining $Zr$ involves,

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