Răspuns:
Explicație:
100 g solutie 1%..................1 g KCl
500 g....................................x
x = 500*1/100 = 5 g KCl
500 - 5 = 495 g apa
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Dupa evaporare
495 - 100 = 395 g apa
5 g KCll
395 + 5 = 400 g solutie
400 g solutie.......................5 g KCl
100 g....................................c
c = 100*5/400 = 1,25%