The total hardness is due to one or a combination of Ca2 , Mg2 , and Fe2 in your sample. It is convenient to express this hardness as though it was entirely due to Ca2 . Making this assumption, determine the number of moles of Ca2 present in the bottled water sample titrated. (enter your answer with 3 significant figures)

Which of the following observations indicates that there is a small, dense, positively charged part in the center of an atom? some uncharged particles are scattered by a gold foil. all uncharged particles are attracted towards a gold foil. all positively charged particles pass straight through a gold foil. some positively charged particles bounce back from a gold foil.