Question

The method used for the purification of Indium is

• A. Vapour phase refining
• B. Liquation
• C. Van Arkel method
• D. Zone refining

Answer 1

The correct option is D Zone refining

Option (b)
Indium is purified by zone refining method.
Zone refining refers to the method of purifying a crystal wherein a thin region of the crystal undergoes melting. This ‘molten zone’ is now moved across the crystal.

The impurities in the metal are melted at the forward edge by the molten zone and move through the block of metal, leaving the solidified pure element behind.

As they move through the block of metal, the impurities in the metal are concentrated in the melt and are transported to one end of the metal block.
The principle of zone refining is that the impurities in an ingot or ore of metal are more soluble in the melt state when compared to the corresponding solid state of the impurities