X-ray diffraction from crystals provides one of the most accurate ways of determining the Avogadro's number. Silver crystallizes in a face-centered cubic lattice with all atoms at the lattice points. The length of an edge of the unit cell was determined by x-ray diffraction to be 4.086 A (408.6pm). The density of silver is 10.50g/cm3. Calculate the mass of a silver atom. Then using the known value of the atomic, calculate Avogadro's number.