5 mg of fluoride ions are present in 2 kg of water. What is the concentration in parts per million?
Answer and explanation
Correct answer: 2.5 ppm
For a dilute aqueous sample, ppm by mass is conveniently expressed as milligrams of solute per kilogram of solution, approximately per kilogram of water. Thus concentration = 5 mg/2 kg = 2.5 mg kg−1, which corresponds to 2.5 ppm. Option B is correct. The approximation is appropriate here because the solution is very dilute.
Frequently asked questions
What is the correct answer to this question?
2.5 ppm
Why is this the correct answer?
For a dilute aqueous sample, ppm by mass is conveniently expressed as milligrams of solute per kilogram of solution, approximately per kilogram of water. Thus concentration = 5 mg/2 kg = 2.5 mg kg−1, which corresponds to 2.5 ppm. Option B is correct. The approximation is appropriate here because the solution is very dilute.
Which subject and chapter does this question cover?
This is a Class 11 Chemistry question. Chapter: Chapter 01: Solutions.
