The dilution factor D is defined as

• A. D = Solute volume / Total volume
• B. D = Total volume / Solute volume
• C. D = Final concentration / Initial concentration
• D. D = Initial concentration / Final concentration

Answer: (A)

Dilution factor tells how much the concentration is reduced when you dilute a solution. When you dilute, you take a certain volume of the stock solution (the part that contains solute) and add solvent to reach a larger final volume. The concentration after dilution is the fraction of the stock that is present in the final mixture, which equals the volume of stock added divided by the final total volume: D = Vs / Vt. This also means the final concentration equals D times the initial concentration: C_final = (Vs/Vt) × C_initial.

For example, if you take 1 mL of stock and dilute it to a total volume of 10 mL, D = 1/10 = 0.1. The solution is a 10-fold dilution, with the final concentration being 0.1 of the original. The other forms would invert this relationship (e.g., final over initial or total over solute) and don’t match this definition.