A compound MpXq has cubic close packing (ccp) arrangement of X. Its unit cell structure shown below. The empirical formula of the compound is:

8 X atoms present at the corners. Atoms contribute to 1 unit cell =18×8=16X atoms present at the face centres. Atoms contribute to 1 unit cell =6×12=3Total X atoms =3 + 1=44 M atoms present at edge centres.  Atoms present in 1 unit cell =4×14=11M atom present at body centre and it contribute completely to 1 unit cellThus, total M atoms in one unit cell = 1+1=2 Ratio is M:X::2:4::1:2 Thus, empirical formula is MX2.