The fraction of volume occupied by atoms in a body centered cubic unit cell is:

Options

A. 0.32
B. 0.48
C. 0.68
D. 0.74

Answer

C

Explanation

For body centre cubic `sqrt3a = 4r`
packing fraction
` = (2 xx 4/3 pi r^3)/(a^3) = (2 xx 4/3 pi ( (sqrt3a)/(4))^3)/(a^3) = (sqrt3 pi)/(8) = 0.68`