An element has a body centred cubic (bcc) structure with a cell edge of 444 pm. The density of the element is 7.2 g/cm3. How many atoms are present in 404 g of the element?

Volume of the unit cell = (444 pm)3                                    =(444x10-10cm)3                                    =8.75x10-23cm3Volume of 404 g of the element =massdensity                                                   =404 g7.2 g cm-3=56.11 cm3∴Number of unit cells in this volume                              =56.11cm38.75×10-23cm3/unit cell=6.41×1023 unit cells