AIIMS 2018 Biology Concentration Units MCQ Question

Option D is correct because it accurately represents the relationships between mass and volume in the context of concentration, specifically that 1 ppm (parts per million) is equivalent to 1 mg of solute per liter of solution, which is a standard unit of measurement in chemistry. The conversions provided in the question clarify that 1000 g equals 1 mg, which is incorrect; rather, 1 g equals 1000 mg, indicating a misunderstanding of mass units. The other options are not relevant as they do not provide any additional information or correct calculations related to the problem. Understanding these conversions is crucial for accurately determining concentrations in solutions, such as H₂O or CO₂ in environmental science.