An ionic compound `A_(x)B_(y)` occurs in fcc type crystal structure with B ion at the centre face and A ion occupying corners of the cube. Give the formula `A_(x)B_(y)`.

Options

A. `AB_(3)`
B. `AB_(4)`
C. `A_(3)B`
D. `A_(4)B`

Answer

A

Explanation

`(1)/(8)` of each corner atom. `(1)/(8)xx8=1`
`:.x=1 and (1)/(2)`of each / one atom at face
`:.(1)/(2)xx6=3 :.y=3`