posted by tweety .
The density of platinum is 21500 kg/m3 and the cell volume is 6.04 x 10-26 L. Determine the number of atoms in the unit cell. Note: the number of atoms in a unit cell is a whole number.
I would convert density in kg/m^3 to g/cc.
Then knowing density and volume (convert volume to cc), calculate mass of the unit cell.
Then #atoms in unit cell*atomic mass Pt/6.022 x 10^23 = mass of unit cell.
The only unknown in that relationship is the # atoms. Calculate that. Post your work if you need further assistance.