Ti and Zr are purified by

Options

A. Baeyer's process
B. Mond's process
C. Mac - Arthur process
D. Van - arkel process

Explanation

To solve the question regarding the purification of Titanium (Ti) and Zirconium (Zr), we need to analyze the given options and identify the correct process used for their purification.

### Step-by-Step Solution:

1. **Identify the Options**: The options provided are:
- A) Baeyer's process
- B) Mons process
- C) MacArthur process
- D) Van Arkel process

2. **Evaluate Baeyer's Process**:
- Baeyer's process is specifically used for the extraction of aluminum from bauxite ore. Therefore, it is not applicable for the purification of Titanium or Zirconium.

3. **Evaluate Mons Process**:
- The Mons process is used for the purification of nickel. This process involves the formation of nickel carbonyl, which is not relevant to Titanium or Zirconium.

4. **Evaluate MacArthur Process**:
- The MacArthur process is used for the extraction of gold from low-grade ores. Thus, it does not pertain to the purification of Titanium or Zirconium.

5. **Evaluate Van Arkel Process**:
- The Van Arkel process is specifically designed for the purification of Titanium and Zirconium. In this process, impure Titanium or Zirconium is reacted with iodine to form volatile iodides (TiI4 or ZrI4).
- These iodides are then heated to produce pure Titanium or Zirconium and iodine gas. The reactions occur at specific temperatures (523 K for iodide formation and around 1700 K for decomposition).

6. **Conclusion**:
- Since the Van Arkel process is the only method applicable for the purification of Titanium and Zirconium, the correct answer is **D) Van Arkel process**.

### Final Answer:
Titanium and Zirconium are purified by **Van Arkel process**.