Question

In a solid AB, having the NaCl structure, B atoms occupy the corners of the cubic unit cell. If all the face centred atoms along one of the axes are removed, then what is the resulting stoichiometry of the solid?

Answer 1

 In NaCl (fcc structure)

Cl^– at centre of face = 6 x (1/2) = 3

Cl^– at corners = 8 x (1/8) = 1

Na⁺ at centre of edge = 12 x (1/4) = 3

Na⁺ at centre of cube = 1 

If face centred, that is Cl^– is removed, along one axis. 

Similarly A₄ B₃