`KCN` forms soluble complex with silver glance.

Answer

To determine whether KCN forms a soluble complex with silver glance (which is primarily silver sulfide, Ag2S), we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Components**:
- KCN (potassium cyanide) dissociates in solution to form K⁺ and CN⁻ ions.
- Silver glance (Ag2S) is an ore of silver, primarily composed of silver and sulfur.

2. **Complex Formation**:
- The cyanide ion (CN⁻) can react with silver ions (Ag⁺) to form a soluble complex.
- The reaction can be represented as:
\[ 2Ag^+ + 2CN^- \rightarrow [Ag(CN)_2]^- \]
- This indicates that two silver ions react with two cyanide ions to form a soluble complex ion, [Ag(CN)₂]⁻.

3. **Balancing the Reaction**:
- The reaction is balanced as shown above, where the number of atoms of each element on the reactant side equals the number on the product side.

4. **MacArthur-Forrest Process**:
- The MacArthur-Forrest process utilizes this soluble complex to extract silver from low-grade ores.
- In this process, the soluble complex formed can be treated with a more electropositive metal (like zinc) to displace silver and obtain pure silver metal.

5. **Conclusion**:
- Since KCN does indeed form a soluble complex with silver ions derived from silver glance, the statement is **true**.

### Final Answer:
The statement "KCN forms a soluble complex with silver glance" is **true**.

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