Which of the following pair is correctly matched ?

Options

A. Copper-Oxidative refining
B. Nickel-Kroll's process
C. Mercury-Distillation
D. Lead-van Arkel method

Answer

To determine which pair is correctly matched among the given options, we will analyze each option one by one.

### Step 1: Analyze Option 1 - Copper-Oxidative Refining
- **Explanation**: Copper is refined through a process known as electrolytic refining, not oxidative refining. In electrolytic refining, impure copper is oxidized at the anode to form copper ions, which then get reduced at the cathode to form pure copper.
- **Conclusion**: This option is incorrect.

### Step 2: Analyze Option 2 - Nickel-Kroll Process
- **Explanation**: The Kroll process is primarily used for the extraction of titanium from its ores, not for nickel. Nickel is typically purified using the Mond process, where nickel reacts with carbon monoxide to form nickel carbonyl.
- **Conclusion**: This option is incorrect.

### Step 3: Analyze Option 3 - Mercury-Distillation
- **Explanation**: Mercury can be purified using the distillation method due to its low boiling point. This method allows for the separation of mercury from other metals and impurities effectively.
- **Conclusion**: This option is correct.

### Step 4: Analyze Option 4 - One-Cycle Method
- **Explanation**: The one-cycle method is used for the purification of titanium and zirconium, not lead. Therefore, this option is also incorrect.
- **Conclusion**: This option is incorrect.

### Final Conclusion
After analyzing all options, the only correctly matched pair is:
- **Option 3: Mercury-Distillation**