5. Calculate the radius of an iridium atom, given that it has an FCC crystal structure, a density of 22.4 g/cm3, and an atomic weight of 192.2 g/mol.
6. A hypothetical metal has the simple cubic crystal structure shown to the right. If its atomic weight is 70.4 g/mol and the atomic radius is 0.126 nm, compute its density.
7. Zirconium has an HCP crystal structure and a density of 6.51 g/cm3. (a) What is the volume of its unit cell in cubic meters? (b) If the c/a ratio is 1.593, compute the values of c and a.