Question

Atoms of element B from HCP lattice and those of element A occupy two thirds of tetrahedral voids. What is the formula of the compound formed by elements A and B.

• A. $A_4{B}_3$
• B. $A_4{B}_6$
• C. $A_8{B}_3$
• D. $A_5{B}_3$

Answer 1

The correct option is A

$A_4{B}_3$

The number of tetrahedral voids formed is equal to twice the number of atoms of element B. But only 2/3 of these tetrahedral voids are occupied by atoms of element A.

Therefore the ratio of number of atoms of A and B is

2x(2/3) : 1 = 4:3

The formula of compound is $A_4{B}_3$