The thing to remember about concentrations expressed in parts per million is that they are calculated by looking at the number of parts of solute present for every
In other words, you're looking for the number of grams of solute present in
Now, you know that your solution must have a concentration of
Your goal here will be to use the solution's parts per million concentration as a conversion factor to calculate the number of grams of sodium chloride, your solute, needed to make this solution.
#1.0 color(red)(cancel(color(black)("g solution"))) * overbrace("100.0 g NaCl"/(10^6color(red)(cancel(color(black)("g solution")))))^(color(blue)("= 100.0 ppm NaCl solution")) = color(darkgreen)(ul(color(black)(1.0 * 10^(-4)color(white)(.)"g NaCl")))#
The answer is rounded to two sig figs, the number of sig figs you have for the mass of the solution.