Correct Answer - Option 2 : 0.68
Concept:
Atomic packing factor (APF) of unit cell is defined as
APF \( = \frac{{{N_{atoms}} \times {V_{atoms}}}}{{{V_{unit\;cell}}}}\)
Calculation:
For BCC unit cell Natoms = 2
√3 a = 4 r
Where, a is size of unit cell and r is radius of atom
\(\therefore APF = \frac{{2\; \times \frac{4}{3}\pi \;{r^3}}}{{{{\left( {\frac{{4\;r}}{{\sqrt 3 }}} \right)}^3}}}\)
∴ APF = 0.68
