Multiple choice

A chemist has two solutions: one is a 20% saline solution, and the other is a 30% saline solution. He wants to mix these two solutions to create a new solution of 250 mL, such that the resulting mixture has the maximum possible percentage of saline. However, the chemist is allowed to use at least 100 mL of the 20% solution. What is the maximum percentage of saline that can be achieved in the final mixture?

  1. 22%

  2. 24%

  3. 26%

  4. 28%

  5. a
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

To maximize saline concentration, use as much of the 30% solution as possible. We need 250 mL total and at least 100 mL of 20% solution. Using exactly 100 mL of 20% and 150 mL of 30% gives (100*0.2 + 150*0.3)/250 = (20+45)/250 = 65/250 = 0.26 = 26%.

AI explanation

To maximize the saline percentage using the rule of alligation, the chemist must use the minimum required amount of the weaker 20% solution. By using 100 mL of the 20% solution, he must add 150 mL of the 30% solution to create the 250 mL total. The amount of saline is (20 mL plus 45 mL) = 65 mL, and 65 mL divided by 250 mL equals 0.26, giving a maximum percentage of 26%.

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