Question

A substance A_xB_y crystallises in an 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 composition of substance A_xB_y.

• A. $A_4{B}_3$
• B. $A{B}_3$
• C. $A_{3}B$
• D. compound cannot be specified

Answer 1

The correct option is B

$A{B}_3$

$Totalnumberof{}^{\prime }{A}^{\prime }atoms=(8\times \frac{1}{8})=1Totalnumberof{}^{\prime }{B}^{\prime }atoms=(6\times \frac{1}{2})=3$

So, the composition is $\Rightarrow A{B}_3$