How much water in ml must be added to dilute 9 ml of a 50% alcohol lotion down to 30% alcohol__________?
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Answer: D. 6
Explanation
Applying the standard dilution formula initial concentration times initial volume equals final concentration times final volume. Multiplying fifty percentage by nine milliliters gives four hundred fifty concentration volume units. Dividing four hundred fifty by thirty percentage yields a final total volume of fifteen milliliters. Solution dilution equations assume the total mass of the solute remains constant while solvent volume increases. Calculating added water requires subtracting the initial solution volume from the computed final volume total. Percentage concentrations represent the ratio of solute volume to total solution volume multiplied by one hundred.
Pharmacists use dilution calculations daily to prepare liquid medications with precise active ingredient concentrations. Chemists dilute stock solutions in laboratories to create working reagents for analytical experiments. Understanding solution concentration principles is essential for medical, chemical, and biological sciences. Option A represents an incomplete subtraction step rather than the true difference in solution volumes. Option B underestimates the required added water volume by miscalculating the final total mixture size. Option C results from an arithmetic error during the final volume subtraction calculation.
- Subject
- Mathematics
- Category
- Mathematics
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- —
- Difficulty
- medium
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