WBJEE 2025 Physics and Chemistry Papers

Let's determine the effective number of atoms for each element in one unit cell of the cubic lattice:
A atoms :
Atoms are placed at the 8 corners of the cube.
Each corner atom is shared by 8 neighboring unit cells.
Effective atoms per unit cell: 8×‌

1

8

=1.
B atoms :
B atoms are located at the center of the cube, which is entirely within the unit cell.
Effective atoms per unit cell: 1.
C atoms :
Atoms are positioned at the center of each of the 12 edges.
Each edge-centered atom is shared by 4 unit cells.
Effective atoms per unit cell: 12×‌

1

4

=3.
With these contributions, the total number of atoms per unit cell is:
‌A=1,
‌B=1,
‌C=3.
Thus, the formula of the compound is: ABC3.
The correct option is Option C.