In a `f.c.c.` arrangement of `A` and `B` atoms, where `A` atoms are at the corners of the unit cell and `B` atoms at the face `-` centres, one of the `A` atom is missing from one corner in each unit cell. The formula of compound is `:`

Options

A. `A_(2)B_(6)`
B. `A_(6)B_(7)`
C. `A_(7)B_(24)`
D. `AB_(4)`

Answer

d

Explanation

Since there are six atoms `(A)` at the correct of the unit cells , so contribution of atoms in `1` unit cell is `(6)/(8)`
Since `3` face -centred atoms `(B)` coordination to one unit cell so , formula is `A_(6//8) B_(3)`
or `A_(6)B_(24) or B_(4)`