What is the best way to compare a concentrated solution to a dilute solution, given the same volume of solution?

How is energy related to the change of state represented by the model? atoms gain energy as a solid changes to a liquid. atoms gain energy as a solid changes to a gas. atoms lose energy as a solid changes to a liquid. atoms lose energy as a solid changes to a gas.

Which of the following are acids or bases? 1. sodium hydrogen 2. barium hydroxide solution 3. carbonate solution

For either problem would be greatly appreciated