Express the concentration of a 0.0390 m aqueous solution of fluoride, f–, in mass percentage and in parts per million. assume the density of the solution is 1.00 g/ml.

ppm = mg/L
or
Kg solution Mass % = Mass of Solute/Mass of solution

0.0390 M = x moles/1L
x = 0.0390 Moles of F-
0.0390 mol x 18.998403 g/mol = 0.7409 g

PPM:
1mg = 1000g
0.7409g = 740.9mg
740.9mg/1L = 740.9mg

Mass Percent:
density 1 g/mL
thus
1 g = 1 mL
thus 1 L = 1 kg
thus 1 L = 1000 g
so,
(0.7409 g/1000 g)*100
 = 0.07409% (m/m)

This is a solution, hope i could