Question

An ionic compound has a unit cell consisting of A ions at the corners of a cube and B ions on the centres of the faces of the cube. The empirical formula for this compound would be

• A. \( A_3B \)
• B. \( AB_3 \)
• C. \( A_2B \)
• D. \( AB \)

Hint:

The empirical formula depends on the number of ions present in the unit cell, considering their positions and contributions.

Answer 1

The Correct Option is C

Step 1: Understanding the Ionic Arrangement.
In the unit cell, A ions are at the corners, and B ions are at the face centers. The number of A ions per unit cell is 8, and the number of B ions per unit cell is 6 (since each face center has half an ion). Therefore, the empirical formula is \( A_2B \).
Step 2: Conclusion.
The correct answer is (C), \( A_2B \).