Question

What is the principle of zone refining of metals?

• A. Greater mobility of the pure metal than that of the impurity
• B. Higher melting point of the impurity than that of the pure metal
• C. Greater noble character of the solid metal than that of the impurity
• D. Greater solubility of the impurity in the molten state than in the solid

Answer 1

The correct option is D Greater solubility of the impurity in the molten state than in the solid

Zone refining is based upon fractional crystallization as the impurity prefers to stay in the melt and on solidification only pure metals solidifies on the surface of melt.
In this process solubility of the impurities in the metal in molten is greater than in solid.