Volume of the unit cell is V= =(4.07x108cm)3 =6.76x10r23cm Density=mass/volume =1.31x1021g/6.76x10r23cm =19.4gcmVolume of the unit cell is V = l3 = (4.07 x 10-8 cm)3 = 6.76 x 10-23 cm3 Density = mass/volume =1.31 x 10-21 g / 6.76 x 10-23 cm3 = 19.4 g cm-3