A solution has 2 mg/mL; the required dose is 10 mg. How many milliliters are needed?

A solution has 2 mg/mL; the required dose is 10 mg. How many milliliters are needed?

• A. 2 mL
• B. 4 mL
• C. 5 mL
• D. 10 mL

Answer: (C)

The main idea is converting a prescribed dose into the volume of solution needed using the concentration. If the solution is 2 mg per mL, each milliliter provides 2 mg. To obtain 10 mg, divide the dose by the concentration: 10 mg ÷ 2 mg/mL = 5 mL. So you need 5 milliliters to deliver 10 mg. Quick check: 2 mL would give 4 mg, 4 mL would give 8 mg, and 10 mL would give 20 mg. Only 5 mL provides the exact 10 mg required. The required volume is 5 mL.

The main idea is converting a prescribed dose into the volume of solution needed using the concentration. If the solution is 2 mg per mL, each milliliter provides 2 mg. To obtain 10 mg, divide the dose by the concentration: 10 mg ÷ 2 mg/mL = 5 mL. So you need 5 milliliters to deliver 10 mg.

Quick check: 2 mL would give 4 mg, 4 mL would give 8 mg, and 10 mL would give 20 mg. Only 5 mL provides the exact 10 mg required. The required volume is 5 mL.