Question

Atoms of element B form hcp lattice and those of the element A occupy 2/3 rd of tetrahedral voids. What is the formula of the compound formed by the elements A and B?

• A. A3B4
• B. A4B3
• C. A2B3
• D. A3B2

Answer 1

Answer: (D)

A3B2

Answer 2

To determine the formula of the compound formed by elements A and B, we need to consider the ratio of the atoms in the compound based on their arrangement in the crystal lattice.

Given that the atoms of element B form a hexagonal close-packed (hcp) lattice, the closest packing ratio for this lattice is 2:1. This means that for every two atoms of element B, there is one atom of element A occupying the tetrahedral voids.

Since the atoms of element A occupy 2/3 of the tetrahedral voids, we can deduce that for every 2 atoms of element B, there will be 2/3 atoms of element A. Simplifying this ratio, we get:

2 atoms B : 2/3 atoms A

To simplify the ratio further, we can multiply it by 3 to eliminate the fraction:

(2 atoms B) x (3 atoms A / 2 atoms B) = 3 atoms A

Therefore, the formula of the compound formed by elements A and B is A3B2.