Roasting is a process in which the ore (mostly sulphide) is heated strongly in the presence of excess of air. The heating should be done at a temperature below the melting point of the ore.
Sometimes roasting may not bring about complete oxidation :
`2CuFeS_(2) + 4O_(2) rarr A + 2FeO + 3SO_(2)`
Find the `A` :

Options

A. `Cu_(2) O`
B. `CuO`
C. `Cu_(2) O`
D. `CuS`

Explanation

To find the compound \( A \) in the reaction given, we need to analyze the roasting process and the chemical equation provided. Here’s a step-by-step solution:

### Step 1: Understand the Reaction
The reaction given is:
\[ 2CuFeS_2 + 4O_2 \rightarrow A + 2FeO + 3SO_2 \]

Here, \( CuFeS_2 \) is chalcopyrite, which is a copper iron sulfide ore. During roasting, it reacts with oxygen.

### Step 2: Identify the Products
From the reaction, we see that two products are already specified: \( 2FeO \) (iron(II) oxide) and \( 3SO_2 \) (sulfur dioxide). We need to determine what \( A \) is.

### Step 3: Balance the Reaction
To find \( A \), we need to balance the reaction. The balanced equation for the roasting of chalcopyrite is:
\[ 2CuFeS_2 + 4O_2 \rightarrow Cu_2S + 2FeO + 3SO_2 \]

### Step 4: Identify \( A \)
From the balanced equation, we can see that \( A \) corresponds to \( Cu_2S \) (copper(I) sulfide).

### Conclusion
Thus, the value of \( A \) in the reaction is:
\[ A = Cu_2S \]