Outline the principples behind the refining of metals by the following methods :
(i) Zone refining method
(ii)Chormatographaphic method

Explanation

To outline the principles behind the refining of metals using the specified methods, we can break down the explanation into two parts: Zone Refining Method and Chromatographic Method.

### (i) Zone Refining Method

1. **Principle of Solubility**: The primary principle behind the zone refining method is that impurities are more soluble in the molten state of a metal than in its solid state. This means that when a metal is melted, the impurities tend to dissolve more readily in the liquid phase.

2. **Process Description**: In this method, a narrow zone of the metal is melted using a heat source, such as a moving heater. As the heater moves along the length of the metal rod, the molten zone travels with it.

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