Multiple choice

4 litre of a solution having 10% acid was mixed with 5 litre of a solution having 16% acid. Six litre of pure acid was then added to the resulting solution. The concentration of acid in the final solution is:

  1. 48%

  2. 50%

  3. 54%

  4. 60%

  5. None of these
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A Correct answer
Explanation

First solution: 4L × 10% = 0.4L acid. Second solution: 5L × 16% = 0.8L acid. Total after mixing: 9L with 1.2L acid. Adding 6L pure acid gives total acid = 7.2L in 15L solution. Concentration = 7.2/15 × 100 = 48%. The key is tracking the absolute amount of acid, not just percentages.

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