A compound is formed by elements of X, Y and Z . Atoms of Z (anions) fcc lattice. Atoms of X (cations) occupy all the octahedral voids. Atoms of Y (cations) occupy `(1)/(3)rd` of the tetrahedral voids. The formula of the compound is

Options

A. `X_3 Y_3, Z_3`
B. `X_3 YZ`
C. `XY_2 Z`
D. `X_2 Y_2 Z`

Answer

A

Explanation

In FCC lattice, there are 4 atoms per unit cell.
`therefore z=4`
Each atom consists of only one octahedral void.
`therefore` Total number of octahedral voids, `x = 1(4) = 4`
Given , Y occupies `(1)/(3)` [ Tetrahedral voids]
Each sphere forms 2 tetrahedral voids.
`therefore Y= (1)/(3) [ 2xx 4] = (8)/(3)`
Formula of compound `= X_4 Y_(8/3) Z_4`
`= X_3 Y_2 Z_3`