Answer: 68%.
- A 52.4%
- B 68%
- C 74%
- D 90%
Correct answer: B. 68%
Explanation: BCC has 2 atoms per unit cell; the packing efficiency works out to approximately 68%.
The three cubic unit cells: Simple Cubic has atoms only at corners; Body-Centred adds one atom at the centre; Face-Centred adds one atom at the centre of each of the 6 faces, giving the highest packing efficiency.
Concept context
Explore the ordered world of crystalline solids: unit cells, packing, defects, and how structure determines electrical and magnetic properties.