Metals of high purity are obtained by zone refining.
Impurities are more soluble in melt in pure metal.

Options

A. If both (A) and ( R) are correct and ( R) is the correct explanation of (A).
B. If both (A) and ( R) are correct, but ( R) is not the correct explanation of (A).
C. If (A) is correct, but ( R) is incorrect.
D. If (A) is incorrect, but ( R) is correct.

Answer

### Step-by-Step Text Solution:

1. **Understanding Zone Refining**: Zone refining is a method used to purify metals. It involves melting a small region (or zone) of a solid metal and then moving this molten zone along the metal rod.

2. **Heating the Metal Rod**: A circular mobile heater is used to heat a specific section of the metal rod. This localized heating causes that section to melt.

3. **Movement of Impurities**: When the metal rod is heated, the impurities present in the solid metal are more soluble in the molten zone than in the solid state. Therefore, as the molten zone forms, the impurities migrate from the solid adjacent areas into the molten zone.

4. **Repetition of the Process**: The circular mobile heater is then moved along the rod, allowing the molten zone to shift. This process is repeated multiple times, causing the impurities to continuously move into the molten zone.

5. **Final Purification**: As the molten zone moves along the rod, the impurities are effectively separated from the pure metal. Eventually, this results in a highly purified metal rod, as the impurities are concentrated in the molten zone and can be removed.

6. **Conclusion**: Thus, the assertion that metals of high purity are obtained by zone refining is correct, and the reasoning that impurities are more soluble in the molten zone than in the pure metal is also correct. The reasoning provides a valid explanation for the assertion.