Question

Atoms of element y form hcp lattice and those of the

element x occupy 1

3 rd ⁄ of tetrahydral voids. What is the

formula of the compound formed by the elements x and y?

(A) X4Y3 (B) X3Y4 (C) X3Y2 (D) X2Y3​

Answer 1

Explanation:

Number of tetrahedral voids formed = 2 x Number of atoms of element Y

Number of atoms of element Y in the ccp unit cell = 4

Number of tetrahedral voids formed = 2 x 4 = 8

Number of tetrahedral voids occupied by atoms of X = 1/3x8

Ratio of the numbers of atoms of X and Y = 8/3:4 =2:3

Hence, the formula of the compound is X2Y3.