Question

The principle of fractional crystallization is involved in which one of the following:
A.Van Arkell’s method
B.Distillation
C.Cupellation
D.Zone refining

Answer 1

Fractional crystallization is a method to refine the substances on the basis of their solubility and Zone refining is a technique based on the principle that the impurities are more soluble in the molten state of metal than in the solid state.

Complete step by step answer:
A method to refine substances based on differences in their solubility is known as Fractional crystallization.
Zone refining is a technique based on the principle that the impurities are more soluble in the molten state of metal than in the solid state. So, we can say that zone refining is based upon fractional crystallization as the impurity prefers to stay in the melt and only pure metals solidify on the surface of melt on solidification. In the process of zone refining, solubility of the impurities in the metal in molten state is greater than in solid state. The principle on which it is based is that impurities are more soluble in the melt than in the solid state of the metal. The impure metal is then heated with the help of circular heaters at one end of the rod of the impure metal. A circular mobile heater is fixed at one end of a rod of impure metal silica reacts with iron oxide and forms iron silicate, which is removed as slag in the process of zone refining.
So, the principle of fractional crystallization is involved in Zone refining.
Therefore, the correct answer is option (D).

Note: Van Arkell’s method is used in the thermal decomposition of the metals.
Distillation is a process of separation of components from the liquid mixture based on the differences in the boiling points of the individual components, concentrations of the components present and vapour pressure of the characteristics of liquid mixtures.
Cupellation is a refining process of metals like gold and silver from the impurities by melting the impure metal in the cupel.