Answer: 56 g/mol.
- A 48 g/mol
- B 56 g/mol
- C 96 g/mol
- D 120 g/mol
Correct answer: B. 56 g/mol
Explanation: M = d × NA × a³ / Z = (5.96 × 6.022 × 10²³ × (4 × 10⁻⁸)³) / 2 = (5.96 × 6.022 × 10²³ × 64 × 10⁻²⁴) / 2 = (5.96 × 0.3854) / 2 × 100 ≈ 56 g/mol (iron).
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.