There are many methods for processing of metals. Out of the following which metals are processed by electrolytic decomposition method ?
(i) Gold (ii) Copper (iii) Potassium (iv) Sodium

Options

A. (i) and (ii)
B. (ii) and (iii)
C. (iii) and (iv)
D. (i) and (iv)

Explanation

To determine which metals among the given options are processed by the electrolytic decomposition method, we can follow these steps:

### Step 1: Understand the Electrolytic Decomposition Method
The electrolytic decomposition method involves passing an electric current through an electrolyte solution containing metal ions. This process leads to the deposition of the corresponding metal at the cathode through a reduction reaction.

### Step 2: Analyze the Given Metals
We have four metals to analyze:
1. Gold (Au)
2. Copper (Cu)
3. Potassium (K)
4. Sodium (Na)

### Step 3: Identify Metals Processed by Electrolytic Decomposition
- **Gold (Au)**: Gold can be extracted using the electrolytic decomposition method. It is often processed from its ores or salts through electrolysis.
- **Copper (Cu)**: Copper is also commonly extracted using the electrolytic method, especially from copper sulfate solutions.
- **Potassium (K)**: Potassium is typically extracted through electrolysis of molten potassium chloride, but it is not usually referred to as electrolytic decomposition in the same context as gold and copper.
- **Sodium (Na)**: Sodium is extracted through the electrolysis of molten sodium chloride, similar to potassium, but again, it is not typically categorized under electrolytic decomposition for processing metals.

### Step 4: Conclusion
Based on the analysis, the metals that are processed by the electrolytic decomposition method are:
- Gold (i)
- Copper (ii)

Thus, the correct answer is (i) Gold and (ii) Copper.

### Final Answer
The metals processed by electrolytic decomposition method are:
- Gold (i)
- Copper (ii)

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