seawater contains approximately 3.5% NaCl by mass and has a density of 1.02g/mL. What volume of seawater contains 1.0 g of sodium? Please Help!

Answer 1

3.5% NaCl w/w means 3.5 g NaCl/100 g soln.
Since the density is 1.02 g/mL, you know that 100 g must have a volume of
v = m/d = 100/1.02 = about 98 but you need to confirm that.
Then 98 x (1/3.5) = ?? mL for 1 gram.