van Arkel Method is used for:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Refining of \(Zr\) and \(Ti\)
The van Arkel method is a vapour-phase refining method. It removes all the oxygen and nitrogen present as impurities in metals such as zirconium and titanium. The crude metal is heated with iodine in an evacuated vessel; the volatile, covalent iodide distils off and is then decomposed on a tungsten filament heated electrically to about 1800 K, where the pure metal deposits:
\( \ce{Zr + 2I2 -> ZrI4} \)
\( \ce{ZrI4} \xrightarrow{1800\,\mathrm{K}} \ce{Zr + 2I2} \)
Titanium is refined in the same way through \( \ce{TiI4} \). The iodine set free is used again.
Why the other options are incorrect
Option (1) Refining of \(Zn\) only — Incorrect. Zinc is a low-boiling metal and is refined by distillation, not through its iodide.
Option (3) Refining of \(Zr\) only — Incorrect. The method is used for titanium as well as zirconium.
Option (4) Refining of \(Ti\) and \(Zn\) — Incorrect. Titanium is right, but zinc is refined by distillation.
Note: This question is from the pre-rationalised NCERT book (2022-23). The topic is not there in the latest NCERT book (2026-27), and it is also out of the CUET 2026 syllabus.
NCERT (Pre-rationalised edition, 2022-23):
Vapour Phase Refining – …
