Solubility = Amount of solute dissolved in 1dm3 of solvent divided by the volume of solvent
Solubility = massmolarmass x 1 dm3
Molar mass of NaCl = 23 + 35.5 = 58.5 g/mol
Solubility = 12758.5 x 1 dm3
= 2.17
= 2.2 moldm−3