Which of the following accurately describes properties of valence

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

What is the molecular weight of copper

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.