An ionic compound made up of atoms A and B has a face-centred cubic arrangement in which atoms A are at the corners and atoms B are at the face-centres. If one of the atoms is missing from the corner, what is the simplest formula of the compound ?

An ionic compound made up of atoms A and B has a face-centred cubic ar

1.	An ionic compound made up of atoms A and B has a face-centred cubic arrangement in which atoms A are at the corners and atoms B are at the face-centres. If one of the atoms is missing from the corner, what is the simplest formula of the compound ?
Answer» SOLUTION :No. of ATOMS of A at the corners=7 (because one A is missing) `therefore` Contribution atoms of A towards unit cell =`7xx1/8=7/8` No. of atoms B at face-centres=6 `therefore` Contribution of ATOM B towards unit cell`=6xx1/2=3` Ratio of A:B=`7/8:3`=7:24 `therefore` FORMULA is `A_7B_24`