There are following extraction process of silver but not:

Options

A. as a side product in electrolytic refining of copper
B. Parke's process in which Zn is used to extract silver by solvent extraction from molten lead
C. by reaction of silver sulphide with KCN and then reaction of soluble complex with Zn
D. by heating `Na[Ag(CN)_(2)]`

Answer

To solve the question regarding the extraction processes of silver, we need to analyze the options provided and determine which one is not a valid extraction method for silver.

### Step-by-Step Solution:

1. **Understanding the Extraction Processes**:
- The question lists various methods for extracting silver. We need to identify each method and see if it is a recognized process for silver extraction.

2. **Analyzing Each Option**:
- **Option A**: As a side product in electrolytic refining of copper.
- This is a valid method. During the electrolytic refining of copper, silver can be recovered as a side product.

- **Option B**: Parkes process.
- The Parkes process is a well-known method for extracting silver from lead. It involves the use of zinc to separate silver from molten lead. This is also a valid method.

- **Option C**: Reaction of silver sulfide with KCN.
- This process involves the reaction of silver sulfide (Ag2S) with sodium cyanide (KCN) to form soluble complexes. This is a recognized method for silver extraction.

- **Option D**: Heating NaAgCN2.
- This option suggests heating sodium silver cyanide (NaAgCN2) as a method of extraction. However, this is not a recognized or valid extraction process for silver.

3. **Conclusion**:
- After analyzing the options, we conclude that **Option D (heating NaAgCN2)** is not a valid extraction process for silver.

### Final Answer:
The extraction process of silver that is NOT valid is **D. Heating NaAgCN2**.