A friend tells you, because composition does not change during a physical changes, the appearance of a substance does not change. is your friend correct? explain why.

That friend is not correct. Physical change is characterized by a change in appearance without any change in composition. So, if the appearance did not change in the situation, then there is no change in the system. This type of change affects the form of a substance but not the composition or the structure of the molecules. Examples of this type of change are ice melting, cutting a paper into half, clay is molded to a new shape, butter melting, water evaporating. The change that involves a change in chemical composition is classified a chemical change. In this type of change, chemical reactions would take place.