Following reactions take place during extraction of gold
`4Au+8CN^(-)+ 2H_(2)O + O_(2) to 4[Au(CN)_(2)]^(-)+ 4OH^(-)`
`2[Au(CN)_(2)]^(-) + Zn to 2Au + [Zn(CN)_(4)]^(2-)`
Zinc in the extraction of gold acts as a/an

Options

A. oxidising agent
B. flux
C. reducing agent
D. decomposing agent

Answer

To determine the role of zinc in the extraction of gold as described in the given reactions, we can analyze the reactions step by step.

### Step 1: Analyze the First Reaction
The first reaction is:
\[ 4Au + 8CN^- + 2H_2O + O_2 \rightarrow 4[Au(CN)_2]^- + 4OH^- \]

In this reaction, gold (Au) is reacting with cyanide ions (CN^-) and oxygen (O_2) to form a complex ion \([Au(CN)_2]^-\). Here, gold is being oxidized from its elemental state (0 oxidation state) to a +1 oxidation state in the complex.

### Step 2: Analyze the Second Reaction
The second reaction is:
\[ 2[Au(CN)_2]^- + Zn \rightarrow 2Au + [Zn(CN)_4]^{2-} \]

In this reaction, the complex ion \([Au(CN)_2]^-\) reacts with zinc (Zn). In this process, the gold is reduced back to its elemental state (0 oxidation state), while zinc is oxidized from 0 to +2 oxidation state.

### Step 3: Determine the Role of Zinc
Since zinc is being oxidized (its oxidation state increases from 0 to +2), it is acting as a reducing agent. A reducing agent donates electrons to another substance, causing that substance to be reduced. In this case, zinc donates electrons to gold, reducing it from a +1 oxidation state in the complex to 0 in its elemental form.

### Conclusion
Thus, in the extraction of gold, zinc acts as a **reducing agent**.

### Final Answer
Zinc in the extraction of gold acts as a reducing agent.

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