Which one of the following is refined by van Arkel method?

The correct answer is Option (1) → Titanium

The van Arkel method is a vapour phase refining method used to remove oxygen and nitrogen impurities from zirconium and titanium. The crude metal is heated with iodine in an evacuated vessel; the volatile iodide is then decomposed on a hot tungsten filament, and the pure metal deposits on it:

    \( \displaystyle \ce{Ti (impure) + 2I2} \xrightarrow{\Delta} \ce{TiI4(g)} \)

    \( \displaystyle \ce{TiI4(g)} \xrightarrow[\text{W filament}]{\text{about 1800 K}} \ce{Ti (pure) + 2I2} \)

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):
Van Arkel Method for Refining Zirconium or Titanium