Assertion : Zirconium can be purificed by Van Arkel method.
Reason : `ZrI_(4)` is volatile and decomposed at `1800 K`.

Options

A. Both assertion and reason are true and reason is the correct explanation of assertion.
B. Both assertion and reason are true but reason is not the correct explanation of assertion.
C. Assertion is true but reason is false
D. Assertion is false but reason is true.

Explanation

To solve the given question, we need to analyze both the assertion and the reason provided.

**Assertion:** Zirconium can be purified by the Van Arkel method.
**Reason:** \( ZrI_4 \) is volatile and decomposes at 1800 K.

### Step-by-Step Solution:

1. **Understanding the Assertion:**
- The Van Arkel method is a process used for the purification of certain metals, including zirconium and titanium. This method involves the formation of a volatile compound of the metal, which can then be decomposed to yield pure metal.

2. **Analyzing the Reason:**
- The reason states that \( ZrI_4 \) (zirconium iodide) is volatile and decomposes at 1800 K. This is an important characteristic because the volatility of \( ZrI_4 \) allows it to be separated from impurities during the purification process.

3. **Reaction Involved:**
- In the Van Arkel method, zirconium reacts with iodine to form zirconium iodide:
\[ Zr + 2I_2 \rightarrow ZrI_4 \]
- Upon heating, \( ZrI_4 \) decomposes back to zirconium and iodine:
\[ ZrI_4 \rightarrow Zr + 2I_2 \]
- This reaction indicates that the process effectively removes impurities, resulting in purified zirconium.

4. **Conclusion:**
- Since both the assertion and the reason are true, and the reason correctly explains why zirconium can be purified using the Van Arkel method, we can conclude that the correct answer is:
- **Both assertion and reason are true, and the reason is the correct explanation of the assertion.**

### Final Answer:
Both assertion and reason are true, and the reason is the correct explanation of the assertion.