What is the percentage by mass of nacl in a saturated solution of sodium chloride at 50 c?

In this solution we are having two components i.e. NaCl and H₂O. So the %age mass of NaCl is calculated by following formula,

%age mass of NaCl  =  (Mass of NaCl / Mass of NaCl + Mass of H₂O) × 100      (1)

Calculating Mass of NaCl at 50°C;

Solubility of NaCl was searched online and was found 36.69 g / 100 mL of water at 50 °C.

Calculating Mass of 100 mL H₂O at 50°C;

Density of H₂O at 50 °C is 0.988 g/ml, so for 100 mL
As,
                           Density  = Mass / Volume

                           Mass  =  Density × Volume

                           Mass  =  0.988 g/mL × 100 mL

                           Mass  =  98.8 g

Putting Masses of NaCl and H₂O in eq. 1,

              %age mass of NaCl  =  (36.69 g / 36.69 g + 98.8 g) × 100

              %age mass of NaCl  =  (36.69 g / 135.49 g) × 100

              %age mass of NaCl  =  27.07 %

You use the atomic number to find out how many protons and neutrons there are in the atom. you use the atomic mass to find out how many protons and electrons there are in the atom.