What causes matter to change?

Matter changes state when the energy is added or taken away from an object

Explanation:

For example, matter changes when you cook an egg. The matter in the egg is recieving energy from the heat of the stove top. This is a Chemical change meaning the object cannot go back to it's original form. In this case the cooked egg cannot go back to it's original form as an egg inside a shell.

I hope this helps :)

indicate valleys, hills, steepness and gentleness of slopes.

explanation:

contour lines on a map indicate elevation, or depth. numeric notations on contour lines refer to the level of elevation, or height about sea level.