Fill in the blanks choosing appropriate word/ words from those given in the brackets : (gravity separation, magnetic separation, absence, presence, `CuFeS_2`, `Cu_2S`, froth flotation, aluminium, iron, smelting, pure, impure, mines, copper, silver, sulfide, zinc, chromium nickel, tin, blister copper, Cus, Fes, thermal, electrical, argentite or silver glance `(Ag_2S)`, cuprous oxide, cuprous sulfide.)
Silver is obtained by adding..........metal to the silver cyanide complex.

Explanation

To solve the question, we need to fill in the blank with the appropriate word from the options provided. The question states: "Silver is obtained by adding __________ metal to the silver cyanide complex."

### Step-by-Step Solution:

1. **Identify the Silver Cyanide Complex**: The silver cyanide complex is represented as \( \text{Ag(CN)}_2^- \). This complex is formed when silver ions react with cyanide ions.

2. **Understanding the Process of Silver Extraction**: In the extraction of silver, particularly from its cyanide complex, a reducing agent is required to convert the silver ions back to metallic silver.

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