Question

Element 'B' forms a CCP structure, and 'A' occupies half of the octahedral voids, while oxygen atoms occupy all the tetrahedral voids. Structure of the bimetallic oxide is:

• A. $A_{2}B{O}_4$
• B. $A{B}_2{O}_4$
• C. $A_2{B}_{2}O$
• D. $A_4{B}_{2}O$

Answer 1

The correct option is B $A{B}_2{O}_4$

Element 'B' forms the CCP structure. So,
$\text{No. of 'B' atoms in unit cell}=N$
$\therefore \text{Number of tetrahedral voids}=2N$
$\text{Number of octahedral voids}=N$
Element 'A' atoms occupy half of the octahedral voids,
$\therefore \text{Number of 'A' atoms in the unit cell}=\frac{N}{2}$
Oxygen atoms occupy all the tetrahedral voids
$\therefore \text{Number of oxygen (O) atoms}=2N$
Hence, Ratio of A, B and O atoms in the unit cell
$=\frac{N}{2}:N:2N$
$\Rightarrow 1:2:4$
Structure of the bimetallic oxide is $A{B}_2{O}_4$.