What is the concentration of a solution, in parts per million, if 0.02 gram of Na3PO4 is dissolved in 1000 grams of water

One way of expressing concentration is by expressing it by parts per million or ppm. Parts per million is equal to 1 milligram of solute per kilogram of solution. The problem is solved as follows:

ppm = 0.02 g (1000mg/1g) / (1000 g + 0.02 g) (1 kg / 1000g) = 2x10^-5 ppm