What happens when a substance undergoes a physical change?
Some physical properties change, but the substace keeps its identity.
No physical properties change, and the substance keeps its identity.
Some physical properties change, and the substance changes its identity.
No physical properties change, but the substance changes its identity.

A physical change is where the chemical make up stays the same. But a chemical change is where the chemical make up changes.

Explanation:

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.