The metal like `Si, Ga` etc., which are used in semiconductors, are purified by ______.

Answer

**Step-by-Step Solution:**

1. **Understanding the Question:**
The question asks for the purification process of metals like silicon (Si) and gallium (Ga), which are commonly used in semiconductors.

2. **Identifying the Purification Process:**
The purification of silicon and gallium is typically done using a specific method. For these metals, the most effective method is known as "zone refining."

3. **Explaining Zone Refining:**
Zone refining is a technique used to purify metals by exploiting the difference in solubility of impurities in the solid and liquid states of the metal. In this process, a molten zone is moved along the length of the metal sample. As the molten zone moves, impurities are carried along with it and are eventually separated from the pure metal.

4. **Visualizing the Process:**
In zone refining, a rod containing the impure metal is heated at one end. The heat creates a molten zone that moves along the rod. As the zone moves, pure metal crystallizes behind it while impurities are left behind in the molten zone, which is then removed.

5. **Conclusion:**
The answer to the question is that metals like silicon and gallium are purified by the process of **zone refining**.

**Final Answer:**
The metal like Si, Ga etc., which are used in semiconductors, are purified by **zone refining**.

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