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.

Answer

AB, structure is same as that of NaCl

Explanation

`{:("Atoms A/unit cell",=8xx1/8" " +,6xx1/2=4),(,"(corners)","(face-centres)"),("Atoms B/unit cell",=12xx1/4" " +,1=4),(,"(edge-corners)","(body-centres)"):}`
`therefore` A:B=4:4=1:1 . So the formula is AB.