A substance `A_(x)B_(y)` crystallises in a face centred cubic (fcc) lattice in which atoms 'A' occupy each corner of the cube and atoms 'B' occupy the centres of each face of the cube identify the correct formula of the compound.

Options

A. `AB_(3)`
B. `A_(4)B_(3)`
C. `A_(3)B`
D. composition cannot be specified

Explanation

To determine the correct formula of the compound \( A_xB_y \) that crystallizes in a face-centered cubic (FCC) lattice, we need to analyze the positions of the atoms within the unit cell.

### Step-by-Step Solution:

1. **Identify the Positions of Atoms:**
- In a face-centered cubic (FCC) lattice, atoms 'A' occupy the corners of the cube, and atoms 'B' occupy the centers of each face of the cube.

2. **Count the Atoms of A:**
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