During an experiment, Stephanie found 4.5 mg of iron in a 750 g water sample. How many parts per million of iron are in the water sample ?

6ppm

Explanation

We'll begin by calculating the concentration of the solution in mg/g. This is illustrated below:

Mass of iron = 4.5mg

Mass of water = 750g

Concentration in mg/g = 4.5/750 = 6×10¯³mg/g.

Now, we can obtain the concentration in ppm as follow:

1mg/g = 1000ppm

Therefore, 6×10¯³mg/g = 6×10¯³ x 1000 = 6ppm.

it is b that is the answer.