In the fcc arrangement of `A` and `B` atoms whose `A` atoms are at corners of the unit cell and `B` are at the face centres one of the `A` atom is missing from one corner in each unit cell. What is the simplest formula of the compound?

Options

A. `A_(7)B_(3)`
B. `AB_(3)`
C. `A_(7)B_(24)`
D. `A_(8)B_(21)`

Answer

C

Explanation

Number of A atoms `=(1)/(8)xx7=(7)/(8)`
Number of B atoms `=6xx(1)/(2)=3`
`A:B=(7)/(8):3=7:24`
Molecular formula `=A_(7)B_(24)`