Answer: r = a√3/4.
- A r = a/2
- B r = a√2/4
- C r = a√3/4
- D r = a√2/2
Correct answer: C. r = a√3/4
Explanation: In BCC, atoms touch along the body diagonal. Body diagonal = a√3. The diagonal passes through 4 radii: 4r = a√3, so r = a√3/4.
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.