A520-gram sample of seawater contains 0.317 moles of nacl. what is the percent composition of nacl in the water?

The answer is in the photo.

3.56 %

Explanation:

Percent composition of NaCl =   x 100

Mass of sea water = 520 g  

Moles of NaCl = 0.317  mol

Molar mass of NaCl = 58.44 g/mol

Mass of NaCl = moles of NaCl x Molar mass of NaCl  

                       =   0.317  mol x 58.44 g/mol  = 18.52 g

Percent composition of NaCl =  x 100 = 3.56 %