In a solid 'AB' having the NaCl structure, 'A' atoms occupy the corners of the cubic unit cell. If all the face centred atoms along one of the axes are removed, then the resultant

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

TestHub · Accepted Answer

Na in NaCl has eight corner and six face atoms and thus, if we remove face centred atom of one axis, then two face atoms are removed. Thus, A is at 8 corners & at 4 face centers.
Number of A atoms per unit cell $= 8 \times \frac{1}{8} + 4 \times \frac{1}{2} = 3$
B present in all octahedral voids, hence
Number of B atoms per unit cell $= 12 \times \frac{1}{4} + 1 = 4$
Thus, formula is $A_{3} B_{4}$ .

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