Weight of one mole of unit cells of NaCl crystals is ––––––––––––

Number of formula units/unit cell of NaCl = 4Explanation:- NaCl has fcc arrangement Cl¯ ions occupy corners and face centresEffective number of Cl¯ ions/unitcelNa+ ions occupy edge centres and body centreEffective number of Na+ ions/unit  cellThus number of NaCl units/unit cell = 4Na+4Cl¯                                                           = 4NaCl unitsWe know,58.5 g of NaCl contian "NA" NaCl units58.5 g of NaCl contain unit cells"X" g of NaCl conain NA unit cells (1 mole of unit cells)     = 234 g