Question

A crystalline solid between A and B has the following arrangement of atoms:
(i) Atoms A are arranged in a CCP array.
(ii) Atoms B occupy all the octahedral voids and half of the tetrahedral voids.
What is the formula of the compound?

• A. $A_{2}B$
• B. $A_3{B}_4$
• C. $A{B}_2$
• D. $A{B}_3$

Answer 1

The correct option is C $A{B}_2$

Let, the number of atoms of A be N.

So, the number of octahedral voids is N.

The number of tetrahedral voids is 2N.

i) There will be one atom of B in the octahedral void.

ii) There will be one atom of B in the tetrahedral void $(\frac{1}{2}\times 2N)$.

Total $2$ atoms of B for each atom of A.

Therefore, the formula of the compound is $A{B}_2$.