Which of the following pairs of metals is purified by van Arkel method ?

Correct option is C

Correct Answer: C — Zr and Ti
 Explanation
The Van Arkel method (also called Van Arkel–de Boer process) is used for obtaining ultra-pure metals of:
 Titanium (Ti) Zirconium (Zr)
These metals are first converted into volatile metal iodides, which are then decomposed on a hot tungsten filament to deposit pure metal.
 Why the other options are incorrect
A — Ni and Fe
Nickel is purified mainly by the Mond’s process (formation of nickel carbonyl).
Iron is purified industrially by oxidation and reduction methods, not by Van Arkel method.
B— Ga and In
Gallium and Indium are purified by zone refining and electrolytic processes.
They do not form stable volatile iodides suitable for the Van Arkel process.
D — Ag and Au
Silver and gold are purified using cupellation, electrorefining, and aqua regia extraction, not Van Arkel.
They already occur in relatively pure forms.