Solid State Question 3
Question: Ammonium chloride crystallizes in a body centred cubic lattice with edge length of unit cell of 390 pm. If the size of chloride ion is 180 pm, the size of ammonium ion would be
Options:
A) 174 pm
B) 158 pm
C) 142 pm
D) 126 pm
Show Answer
Answer:
Correct Answer: B
Solution:
[b] For bcc structure Interionic distance $ ={{r}^{+}}+{{r}^{-}}=\frac{\sqrt{3}}{2}a $ (a = edge length) $ r _{NH_4^{+}}^{+}+r _{c{{l}^{-}}}^{-}=\frac{\sqrt{3}}{2}a $
$ r _{NH_4^{+}}^{+}+180=\frac{\sqrt{3}}{2}\times 390 $
$ r _{NH_4^{+}}^{+}=338pm-180pm=158pm $
BETA
