What is the concentration of a solution in mg/ml if 1 liter contains 500 mg of the active ingredient?

To determine the concentration of the solution in mg/ml, we need to start by converting the amount of active ingredient from milligrams to milliliters, since we have 1 liter of solution.

1 liter is equivalent to 1000 milliliters. If the solution contains 500 mg of the active ingredient in 1000 ml, the concentration can be calculated by dividing the total amount of active ingredient by the total volume of the solution:

Concentration = (amount of active ingredient in mg) / (volume of solution in ml)

Concentration = 500 mg / 1000 ml

When we perform this calculation, we find:

Concentration = 0.5 mg/ml

This value correctly represents the concentration of the active ingredient in the solution. Therefore, the correct answer is 0.5 mg/ml, reflecting how much of the active ingredient is present in each milliliter of the solution. This calculation is essential for determining dosages and ensuring proper medication administration in a pharmacy setting.