Answer:

volume of thesolution = 15.0 mL

      mass of the solution =15.78 g

      mass of the solute(NaCl)   = 3.26 g

         ∴ % m/m = (3.26 g / 15.78g ) *100

                          = 20.65 %

             % m /v = ( 3.26 g / 15.0 mL ) * 100

                          = 21.73 %

          Number of moles of the solute = 3.26 g / 58.44g/mol

                                                           =0.055 mol

            volume of the solution = 15.0 mL = 0.015L

            ∴ molarity of the solution = 0.055 mol / 0.015L

                                                      = 3.66 M