A compound made up of elements `A` and `B` crystallizes in the cubic structures. Atoms `A` are present on the corners as well as face centres whereas atoms `B` are present on the edge centres centres as well as body centre. What is the formula of the compound? Draw the structure of its unit cell.

Explanation

Number of atoms of 'A'
(a)From 8 corners =`1/8`=1
From 6 faces =`1/2xx6`=3 , `therefore` Total atoms of A =3+1=4
Number of atoms of 'B'
(a)From body centre=1
(b)From edge centres =`1/4xx12`=3
Total=4
A:B=4:4 or 1:1
Hence, formula of compound =AB