`underset(("Sulphide ore")) (A) + NaCN overset ("Air") hArr underset(("Complex"))(B) +Na_(2) S overset(O_(2))rarr C`.
`C` is.

Options

A. `Na_(2) SO_(4)`
B. `Na_(2)SO_(3)`
C. `Na_(2) O`
D. `Na_(2) O_(2)`

Explanation

To solve the question, we need to analyze the reactions involving the sulfide ore and the reagents provided. Let's break it down step by step.

### Step-by-Step Solution:

1. **Identify the Sulfide Ore**:
The question mentions a sulfide ore. A common example of a sulfide ore is silver sulfide (Ag₂S).

**Hint**: Remember that sulfide ores typically contain metal ions combined with sulfur.

2. **Reaction with Sodium Cyanide (NaCN)**:
When silver sulfide (Ag₂S) reacts with sodium cyanide (NaCN) in the presence of air (which provides oxygen), it forms a complex. The reaction can be represented as:
\[ \text{Ag}_2\text{S} + \text{NaCN} \xrightarrow{\text{Air}} \text{Na}_2[\text{Ag(CN)}_2] \]
This complex is known as sodium dicyanoargentate(I).

**Hint**: Look for the formation of complexes when metal sulfides react with cyanides in the presence of oxygen.

3. **Reaction of the Complex with Sodium Sulfide (Na₂S)**:
The complex formed (Na₂[Ag(CN)₂]) then reacts with sodium sulfide (Na₂S). The reaction can be represented as:
\[ \text{Na}_2[\text{Ag(CN)}_2] + \text{Na}_2\text{S} \xrightarrow{\text{O}_2} \text{Na}_2\text{SO}_4 + \text{Ag} \]
This reaction produces sodium sulfate (Na₂SO₄) and silver (Ag).

**Hint**: Consider the products formed when a metal complex reacts with sulfides and oxygen.

4. **Identify Compound C**:
From the above reaction, we can conclude that the compound C formed is sodium sulfate (Na₂SO₄).

**Hint**: The final product of the reaction will often be a salt, especially when dealing with sulfides and sulfates.

### Final Answer:
C is sodium sulfate (Na₂SO₄).