Question

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

(a) X₃Y₄ 

(b) X₄Y₃

(c) X₂Y₃ 

(d) X₂Y

Answer 1

(b) : Number of Y atoms per unit cell in ccp lattice
(N) = 4
number of tetrahedral voids = 2N = 2 × 4 = 8
number of tetrahedral voids occupied by X
= 2/3^rd of the tetrahedral void = 2/3 × 8 = 16/3
Hence the formula of the compound will be
X_16/3 Y₄ = X₄ Y₃