Solid State Question 94
Question: A crystal is made of particles A and B. A forms fcc packing and B occupies all the octahedral voids. If all the particles along the plane as shown in the figure are removed, then the formula of the crystal would be:
Options:
A) $ AB $
B) $ A_5B_7 $
C) $ A_7B_5 $
D) none of these
Show Answer
Answer:
Correct Answer: A
Solution:
[a] Effective number of (particles removed $ =4\times \frac{1}{8}+2\times \frac{1}{2}=\frac{3}{2} $
Effective number of B particles removed
$ =2\times \frac{1}{4}+1=\frac{3}{2} $
Effective number of B particles present in a unit cell $ =4-\frac{3}{2}=\frac{5}{2} $
A : B
$ \frac{5}{2} $ : $ \frac{5}{2} $ or $ 1:1 $
BETA
