Answer: 2.16 g/cm³.
- A 1.54 g/cm³
- B 2.16 g/cm³
- C 3.00 g/cm³
- D 4.28 g/cm³
Correct answer: B. 2.16 g/cm³
Explanation: d = ZM/(NA × a³) = (4 × 58.5)/(6.022 × 10²³ × (5.64 × 10⁻⁸)³) = 234/(6.022 × 10²³ × 1.794 × 10⁻²²) = 234/108.07 ≈ 2.16 g/cm³.
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.