Question

In a solid AB having the NaCl structure, A atoms occupy the corners of the cubic unit cell. If all the face centred atoms along one of the axis are removed. what would be the resultant stoichiometry of solid? 

Answer 1

AB has NaCl structure, i.e., 8 corner and 6 face centred atoms. If we remove face centred atoms of one axis, two face centred atoms are removed. Thus, A is at 8 corners and B is at four faces.

∴ Contribution of A = 8/8 =1

Contribution of B = 4/2 = 2 

∴ Stoichiometry of resultant solid is AB₂ .