An IV infusion delivers 20 units of a medication in 1 liter of 0.9% NaCl. How many units are present per milliliter?

• A. 2
• B. 0.02
• C. 0.2
• D. 0.002

Answer: (B)

When you know the total amount of drug and the total volume, you find the concentration by dividing units by milliliters. Here, 20 units are in 1 liter. Convert the volume to milliliters: 1 liter is 1000 mL. So the concentration is 20 units / 1000 mL = 0.02 units per mL. This matches the given infusion strength.

If you test the other numbers: 2 units per mL would imply 20 units in only 10 mL, not in 1 liter; 0.2 units per mL would require 200 units per liter; 0.002 units per mL would yield only 2 units per liter. None of those align with 20 units in 1 liter, so 0.02 units per mL is the correct rate.