Question

A compound formed by elements A and B has cubic structure in which A atoms are at the corners of the cube and B atoms are at the face centres. The formula of the compound will be__________.

• A. $A_4{B}_3$
• B. $A_{2}B$
• C. $A{B}_3$
• D. $A_2{B}_3$

Answer 1

Answer: (C)

$A{B}_3$

Number of atoms A present per unit cell $=\frac{1}{8}\times 8=1$
Number of atoms B present per unit cell $=6\times \frac{1}{2}=3$
Ratio of $A:B=1:3$
Hence, the formula is $A{B}_3$.