The metal that can be purified economically by fractional distillation method is :

Solution

Chemistry ma’am · 3 steps

Distillation works only for a metal that boils easily, and zinc boils at about 907 °C, far below the rest.

1. When distillation works. Distillation boils the metal away from its impurities and condenses it back pure. That is cheap only if the metal has a fairly low boiling point, as in Zn, Cd and Hg.

   Metal	Boiling point	Usual refining
   Fe	about 2860 °C	not refined by distillation
   Zn	about 907 °C, low	fractional distillation
   Cu	about 2560 °C	electrolytic refining
   Ni	about 2910 °C	Mond process

2. Why fractional. Crude zinc usually carries cadmium and lead. Cadmium boils lower than zinc (about 767 °C) and lead much higher, so careful fractional distillation separates all three.
3. So. Only zinc is volatile enough to be distilled economically, so the answer is (b) Zn.

The idea to keep. Match the refining method to the property it uses. Distillation needs a low-boiling metal (Zn, Cd, Hg). Liquation needs a low melting point. Mond and van Arkel need a volatile compound.

Answer from the NTA final answer key. Solution by PrepWiser.