Question

In a compound, atoms of element $Y$ form ccp lattice and those of element $X$ occupy two-third of tetrahedral voids. The formula of the compound will be:

• A. $X_{2}Y$
• B. $X_3{Y}_4$
• C. $X_4{Y}_3$
• D. $X_2{Y}_3$

Answer 1

The correct option is C $X_4{Y}_3$

Number of effective $Y$ atoms in a unit cell $=4$

Number of effective $X$ atoms in a unit cell $=8\times \frac{2}{3}=\frac{16}{3}$

So, formula of the compound

$=X_{16/3}{Y}_4=X_{1/3}{Y}_{1/4}=X_4{Y}_3$

Option C is correct.