Answer: 8.9 g/cm 3.
- A 4.5 g/cm<sup>3</sup>
- B 6.2 g/cm<sup>3</sup>
- C 7.4 g/cm<sup>3</sup>
- D 8.9 g/cm<sup>3</sup>
Correct answer: D. 8.9 g/cm<sup>3</sup>
Explanation: For FCC, a = 2sqrt2 r = 362 pm; d = (4 x 63.5)/(6.022 x 10<sup>23</sup> x (3.62 x 10<sup>-8</sup>)<sup>3</sup>) = 8.9 g/cm<sup>3</sup>.
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.