Question

An ionic solid $A^{\oplus }{B}^{\ominus }$ crystallises in a bcc lattice. The distance between a cation and an anion in the lattice is 338 pm. The edge length of cell is:

• A. 338 pm
  
• B. 390.3 pm
  
• C. 292.7 pm
  
• D. 507 pm

Answer 1

The correct option is B 390.3 pm


For bcc
$(r_{+}+r_{-})=\frac{\sqrt{3}}{2}a$

$338pm=\frac{\sqrt{3}}{2}a\Rightarrow a=390.3$ pm