Answer: π/6.
- A π/4
- B π/6
- C π/3
- D 2π/3
Correct answer: B. π/6
Explanation: Volume of one atom = (4/3)πr³. Volume of unit cell = a³ = (2r)³ = 8r³. Packing fraction = (4/3)πr³ / 8r³ = π/6 ≈ 0.5236 (52.36%).
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.