Question

ina solid AB having NaCl structure atoms occupy the corners of cubic unit cell if all the edge centred along one of the axes are removed then resultant stiochiometry of solid is
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Answer 1

Explanation:

ANSWER

According to the structure of NaCl

Here,

′

A

′

will occupy 8 corners of cubic unit cell which will contribute

8

1

each to the cube

therefore 8×

8

1

=1

and 6 face centered atoms will contribute

2

1

to the cube

Hence 6×

2

1

=3

Therefore total contribution of atom'A' is 3+1=4

Now B occupies octahedral voids (NaCl structure) which contributes 1/4

therefore 1+12×

4

1

=4

So the formula is A is-

A

4

B

4

orAB

Now we are removing all face centered atoms along one axis-

so the number of atoms removed from cube are 2

so contribution from 'A' remains 8×

8

1

(corneratoms)+4×

2

1

(facecenteredatoms)=3

so the resultant becomesA

3

B

4