# In a sodium chloride type structure of A andd B,4A atoms are removed from the edges and 4Batoms are removed from corners.The formula of the new compound will be 1)AB 2)AB2 3)A3B 4)A6B7

Therefore, before removing face centered atoms:

The number of 'B' atoms = (8 x 1/8) + (6 x 1/2) = 1 + 3 = 4 [there are 8 'B' atoms at the corners and 6 'B' atoms at the face centers]

The number of 'A' atoms = (12 x 1/4) + (1 x 1) = 3 + 1 = 4 [there are 12 'A' atoms at the edges and 1 'A' atom at the center of the unit cell]

After removing of A and B atoms :

The number of 'B' atoms = (4 x 1/8) + (6 x 1/2) = 0.5 + 3 = 3.5 [there are now only 4 'A' atoms at the face centers]

The number of 'A' atoms = (8 x 1/4) + (1 x 1) = 2 + 1 = 3

So the formula of compound = A_{3}B_{3.5}

In simple whole number ratio = A_{6}B_{7}

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