Which of the following is the most common unit for expressing the concentration of a solution in terms of molarity?

• A. mol/L
• B. g/L
• C. ppm
• D. mol/kg

Answer: (A)

Verified step by step guidance

1. Understand that molarity is defined as the number of moles of solute dissolved per liter of solution.
2. Recall the formula for molarity: \(M = \frac{\text{moles of solute}}{\text{liters of solution}}\).
3. Recognize that the unit for molarity is therefore moles per liter, often written as mol/L.
4. Compare the given options: mol/L, g/L, ppm, and mol/kg, and identify which matches the molarity definition.
5. Conclude that mol/L is the most common and correct unit for expressing molarity.