Metal with low melting point containing impurities of high melting point can be purified by

Options

A. Zone refining
B. Vapor phase refining
C. Distillation
D. Liquation

Answer

To purify a metal with a low melting point that contains impurities with a high melting point, the most suitable method is liquefaction. Here’s a step-by-step explanation of the process:

### Step-by-Step Solution:

1. **Understanding the Problem**: We have a metal that has a low melting point and is mixed with impurities that have a higher melting point. The goal is to separate the pure metal from these impurities.

2. **Identifying the Suitable Method**: Among the methods of purification available (distillation, zone refining, vapor phase refining, and liquefaction), we need to determine which one is appropriate for our scenario.

3. **Evaluating Distillation**: Distillation is typically used for separating liquids based on their boiling points. Since we are dealing with metals and their melting points, this method is not suitable.

4. **Evaluating Zone Refining**: Zone refining is effective for purifying metals like germanium and silicon, which require ultra-pure forms. This method involves melting a small zone of the metal and moving it along the block, allowing impurities to segregate. However, it is not specifically designed for low melting point metals with high melting point impurities.

5. **Evaluating Vapor Phase Refining**: This method involves converting the metal into a volatile compound and then decomposing it to retrieve the pure metal. It is generally used for metals like titanium and zirconium, not for low melting point metals.

6. **Choosing Liquefaction**: Liquefaction is the process where a mixture of metals is heated. The low melting point metal will melt and can be collected, while the higher melting point impurities remain solid. This method is ideal for the situation described in the question.

7. **Conclusion**: Therefore, the correct method to purify a low melting point metal containing high melting point impurities is **liquefaction**.

### Final Answer:
**Liquefaction** is the method used to purify a metal with a low melting point that contains impurities with a high melting point.

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