Pls solve

Q. A cubic unit cell has Fee symmetry of A atoms and B atom lies at all octahedral voids. If atoms bisecting on axis in two halves with a plane are all removed formula will be 

  (1) AB                              (2) AB2                   (3) A2B                             (4) A2B3

Dear student

A has fcc  symmetry.
Thus no.of A atoms :  8 x 1/8 +6 x1/2 = 4
No.of octahedral voids occupied by B atoms = 4
 If atoms bisecting on axis in two halves with a plane are all removed the
No.of A atoms : 8 x 1/8 + 4 x 1/2 x1/2 =2
Only one B atom will be effected, So 4-1 =3
Thus the formula becomes: A2B3
option (4) is correct

Regards

 

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