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. $AB$

Answer 1

Answer: (B)

$AB_3$

Answer 2

Number of A ions in the unit cell $= \frac{1}{8} \times = 1$ Number of B ions in the unit cell $= \frac{1}{2} \times 6 = 3$ Hence empirical formula of the compound $= AB_3$