What did Louis Pasteur hypothesize?

Why do cells appear different in distilled water than they do in 10% salt water?

Find the mass, in grams, of 5.00*10^23 molecules of f2

A4.86 g piece of metal was placed in a graduated cylinder containing 15.5 ml of water. the water level rose to 17.3 ml. what is the density of the metal. i need the steps of how to solve it to so i can use a formula to work out other problems.