Agovernment laboratory wants to determine whether water in a certain city has any traces of fluoride and whether the concentration exceeds the recommended 4.00 ppm. a 5.00-g sample of this water is found to have 0.152 mg of fluoride. should the water be declared safe for drinking?

3.04 ppm < 4.00 ppm, safe to drink

7.60 ppm > 4 ppm, safe to drink

30.4 ppm > 4 ppm, unsafe to drink

30,400 ppm > 4 ppm, unsafe to drink

The water is unsafe to drink because 30.4 ppm > 4 ppm.

Explanation: The recommended concentration of fluoride in the water is 4.00 ppm. If the concentration of fluoride increases the recommended limit, the water is unsafe to drink and vice-versa.

Parts Per Million (ppm) is the measurement of the concentration of the solution. It is expressed in mg/kg, which means:

We are given a sample of 5.00 grams and the solute is fluoride which has a weight of 0.152 mg.

Weight of the sample = 5.00 grams = 0.005 kg     (Conversion factor: 1 kg = 1000g)

Putting values in ppm equation, we get:

As the ppm value is more than the recommended value. Hence, the water is unsafe to drink.