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peste 400g de solutie cu concentratia 40'/, se adauga 400 g de apa care este concentratia finala a solutiei obtinute

Răspuns :

Formula: C% = md/ms × 100

40% =md/400 ×100
40=md/4
md=40×4
md=160
ms final=400+400=800g solutie
C%final=160/800 ×100
C%final= 16/80×100
C%final= 160/80
C%final=20