Question

A compound formed by elements X and Y crystallizes in a cubic structure in which the X atoms are at the corners of a cube and the Y atoms are at the face - centered . The formula of the compound is :-

• A. $XY$
• B. $X_{3}Y$
• C. $X{Y}_2$
• D. $X{Y}_3$

Answer 1

The correct option is D $X{Y}_3$

In a cubical unit cell:

$\text{Contribution for a corner particle is}=\frac{1}{8}$
$\text{Contribution for a face centre particle is}=\frac{1}{2}$
$\text{Total X atoms in a unit cell}=(8\times \frac{1}{8})=1$
For Y :
$\text{Total Y atoms in a unit cell}=(6\times \frac{1}{2})=3$
Formula of the compound is :
$X{Y}_3$