Complex formation for cyanide method is used for the extraction of

Options

A. Cu
B. Fe
C. Hg
D. Ag

Explanation

To solve the question regarding the complex formation for the cyanide method used in the extraction of metals, we can break it down into the following steps:

### Step-by-Step Solution:

1. **Understanding the Cyanide Method**: The cyanide method, also known as cyanidation, is a hydrometallurgical technique used to extract precious metals from their ores. This method primarily involves the use of sodium cyanide to form complexes with metals.

2. **Identifying the Metals Extracted**: The cyanide method is particularly effective for extracting noble metals such as gold (Aurum) and silver. These metals form stable complexes with cyanide ions.

3. **Formation of Cyanide Complexes**: When ores containing silver or gold are treated with sodium cyanide, they form soluble complexes. For example, silver forms a complex with cyanide ions, resulting in the formation of sodium argentocyanide.

4. **Reduction of Complexes**: The formed cyanide complexes can be reduced using reducing agents such as zinc. This reduction leads to the precipitation of the metal from the complex.

5. **Conclusion**: Therefore, the cyanide method is primarily used for the extraction of silver (Ag) and gold (Au).

### Final Answer:
The complex formation for the cyanide method is used for the extraction of **silver and gold**.

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