1 L water contains 0.05 g lead ions. Assuming a very dilute solution what is the concentration in ppm?
Answer and explanation
Correct answer: 50 ppm
For a very dilute aqueous solution, 1 L of water is approximately 1 kg because water has density close to 1 g mL−1. The lead-ion mass is 0.05 g, which equals 50 mg. Therefore, concentration = 50 mg ÷ 1 kg = 50 mg kg−1, and mg kg−1 is numerically equal to ppm. Hence option B is correct; the other choices arise from decimal or unit-conversion errors.
Frequently asked questions
What is the correct answer to this question?
50 ppm
Why is this the correct answer?
For a very dilute aqueous solution, 1 L of water is approximately 1 kg because water has density close to 1 g mL−1. The lead-ion mass is 0.05 g, which equals 50 mg. Therefore, concentration = 50 mg ÷ 1 kg = 50 mg kg−1, and mg kg−1 is numerically equal to ppm. Hence option B is correct; the other choices arise from decimal or unit-conversion errors.
Which subject and chapter does this question cover?
This is a Class 11 Chemistry question. Chapter: Some Basic Concepts of Chemistry. Topic: Mole concept and molar mass.
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