Iodine has an orthorhombic unit cell for which the a,

Iodine has an orthorhombic unit cell for which the a, b, and c lattice parameters are 0.479, 0.725, and 0.978 nm, respectively.
(a) If the atomic packing factor and atomic radius are 0.547 and 0.177 nm, respectively, determine the number of atoms in each unit cell.
(b) The atomic weight of iodine is 126.91 g/mol; compute its theoretical density.