In a compound, atoms of the element Y form ccp lattice and those of the element X occupy `2//3 rd` of tetrahedral voids. The formula of the compound will be :

Options

A. `X_(4)Y_(3)`
B. `X_(2)X_(3)`
C. `X_(2)Y`
D. `X_(3)X_(4)`

Answer

A

Explanation

Y occupies ccp lattice, it contributes at corner as 1 atom in unit cell and atom at corner is equal to number of octahedral voids. Tetrahedral voids are twice that of octahedral voids and hence
No. of Octahedral voids N
No. of atoms at corner N
No of tetrahedral voids 2N
It occupies 2/3 of tetrahedral voids, contribution to the unit cell `2//3 xx 2N= 4N//3`
`X:Y`
`N : 4N//3`
3:4
Formula is `X_(3)Y_(4)`