Solid State Question 200
Question: In a solid ‘AB’ having the $ NaCl $ structure, ‘A’ atoms occupy the corners of the cubic unit cell. If all the face-centered atoms along one of the axes are removed, then the resultant stoichiometry of the solid is
[IIT Screening 2001]
Options:
A) $ AB_2 $
B) $ A_2B $
C) $ A_4B_3 $
D) $ A_3B_4 $
Show Answer
Answer:
Correct Answer: D
Solution:
There were 6 A atoms on the face-centres removing face-centred atoms along one of the axes means removal of 2 A atoms. Now, number of A atoms per unit cell $ =\underset{(corners)}{\mathop{8\times \frac{1}{8}}}+\underset{(face-centred)}{\mathop{4\times \frac{1}{2}=3}} $ Number of B atoms per unit cell $ =\underset{(edgecentred)}{\mathop{12\times \frac{1}{4}}} $ + $ \underset{(bodycentred)}{\mathop{\underset{{}}{\mathop{1=4}}}} $ Hence the resultant stoichiometry is $ A_3B_4 $
BETA
