Q. Percentage of free space in cubic close packed structure and in body centred packed structure are respectively
A) 30% and 26%
B) 26% and 32%
C) 32% and 48%
D) 48% and 26%
Explanation
(b)
Packing fraction of ccp $= \frac{\pi}{3\sqrt{2}} = 0.74 \Rightarrow 74\%$
% free space in ccp = 26%
Packing fraction of bcc $= \frac{\pi\sqrt{3}}{8} = 0.68 \Rightarrow 68\%$
% free space in bcc = 32%
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.