Name the method used for refining of :
(a). Zirconium.
(b). Nickel.

Explanation

To answer the question regarding the methods used for refining zirconium and nickel, we can follow these steps:

### Step 1: Understand the refining methods
The refining of metals can be done through various methods. For zirconium and nickel, we will focus on vapor phase refining techniques.

### Step 2: Identify the refining method for zirconium
Zirconium is refined using the **Van Arkel process**. This method involves the formation of a volatile compound of zirconium, specifically zirconium iodide (ZrI4), which is then decomposed to yield pure zirconium.

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