The length of the unit cell of sodium chloride approximately in picometers, if density of NaCl is 2.17 × 103 kg m-3 and molecular weight 58.5×10-3 kg mol-1 is

NaCl is face centered cubic lattice so that number of NaCl molecules in a unit cell (Z) = 4We know, density d=MZa3N0were, a = length of the unit cellVolume =a3=MZdN0=58.5×10−3×42.17×103×6.02×1023=1.79 × 10-28 m3a = 5.64 × 10-10 ma = 5.64 Ao = 564 pm