Why isn't mass number listed with each element on the periodic table?

The diagram below shows a cell placed in a solution.a cell is shown placed inside a beaker. it is labeled cell. the solution inside the beaker is labeled 40% salt solution and the solution inside the cell is labeled 20% salt solution.only water is allowed to move in and out of the cell. what will most likely happen to the cell? it will expand as water moves out of it. it will shrink as water moves out of it.it will expand as water moves into it. it will shrink as water moves into it.

What is the mass of naoh that would have to be added to 500 ml of a solution of 0.20 m acetic acid in order to achieve a ph of 5.0?

The graph indicates the running route for tobias. which best describes his run? from time 0 to 6, he went fast and then slowed down. from time 6 to 10, he was at his slowest. from time 12 to 14, he went very slow. from time 14 to 18, he went toward the starting point.