Answer: a√2/4.
- A a/2
- B a√2/4
- C a√3/4
- D a/4
Correct answer: B. a√2/4
Explanation: Face diagonal = a√2. Along the face diagonal: 4r = a√2, so r = a√2/4.
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.