The atomic radius of metal X is 1.20 * 102 picometers (pm) and a crystal of metal X has a unit cell that is face-centered cubic. Calculate the density of metal X (atomic weight = 42.3 g/mol).

The density of the metal can be determined through the formula [n*MW] / Na*[a^3]. substituting, we get,

d = [n*MW] / Na*[a^3]

d = [4 atoms*42.3 g/mol] / [6.022 x 1023atoms/mol * (sqrt 8 * 1.20x10-10) ^3]

d = 0.719 g/cm3