Water — Question 2

Given,
Mass of solute = 15 g
Mass of solvent = 285 g
Mass of solution = Mass of solute + Mass of solvent
              = 15 + 285
              = 300

Mass percent = $\dfrac{\text{Mass of solute}}{\text{Mass of solution}}$ x 100

= $\dfrac{15}{300}$ x 100

= 5%

∴ Concentration of sodium chloride in 285 g of water is 5%