Răspuns :
c/100=md/ms => 20/100=400/ms => ms=2000g solutie de NaOh => 400 g NaOH si 1600 g H2O
md = ms * c/100 = 400 * 20 /100 = 80 g
ms = md + m apa => m apa = 400 - 80 = 320 g
ms = md + m apa => m apa = 400 - 80 = 320 g