Q. Percentage of free space in a body centred cubic unit cell is
A) 28%
B) 30%
C) 32%
D) 34%
Explanation
[Solution from source] In bcc, 2 atoms of radius r = √3a/4 occupy 2 × (4/3)πr³ = (√3π/8)a³ ≈ 0.68a³, a packing efficiency of 68%. The free space is 100 − 68 = 32%. 26% would be the value for fcc/hcp. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.