What is important about the properties of a substance that has undergone a chemical
change?

The substances created during chemical reactions, on the other hand, do not simply revert to their initial state. The most essential thing to remember is that the makeup of a material does not change when it undergoes a physical change, but it does change when it undergoes a chemical change.

the most important thing for you to remember is that in a physical change composition of a substance does not change and in a chemical change the composition of a substance does change

in cartography, a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level. a contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes.

explanation: