Solid State Question 185
Question: In the rock salt structure, the number of formula units per unit cell is equal to
Options:
A) 1
B) 2
C) 3
D) 4
Show Answer
Answer:
Correct Answer: D
Solution:
In $ NaCl $ (rock salt) : Number of $ N{{a}^{+}} $ ions $ =12 $ (at edge centers) $ \times \frac{1}{4}+1 $ (at body centre) $ \times 1=4 $ .
Number of $ C{{l}^{-}} $ ions $ =8 $ (at corners) $ \times \frac{1}{8}+6 $ (at face centre) $ \times \frac{1}{2}=4 $ . Thus 4 formula units per unit cell.
BETA
