Multiple choice

How many litres of water must be evaporated from 20 litres of 3 % solution to get a 5 % solution?

  1. 8 litre

  2. 12 litre

  3. 9 litre

  4. 6 litre

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

Initial solution: 3% of 20L = 0.6L acid. After evaporating x litres: 20 - x litres remaining with 0.6L acid = 5% concentration. So 0.6 = 0.05(20 - x), giving x = 8L.

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