Final answer:
Physical changes involve a change in state but not in composition, like water being frozen into ice. Chemical changes involve transforming into a different substance altogether like the process of rusting. To determine whether a change is physical or chemical, we must check if the substance has transformed into a different kind of matter.
Step-by-step explanation:
In the provided scenarios, we're asked to determine whether the changes described are physical or chemical changes. A physical change is characterized by a change in state, but not in composition. For instance, if water is frozen into ice, it's still water, hence, it's a physical change.
Physical properties, such as hardness and boiling point, and physical changes, such as melting or freezing, do not involve a change in the composition of matter.
On the other hand, a chemical change involves a transformation into a different substance altogether. Examples of chemical changes include reactions that are performed in a lab, all forms of combustion (burning), food being cooked, digested, and rotting.
The formation of rust is a chemical change because rust is a different kind of matter than the iron, oxygen, and water present before the rust formed.
Therefore, whether a process involves a physical or chemical change depends on if the process leads to a difference in the type of matter present.
Learn more about Physical and Chemical Changes