Final answer:
Water is an example of a substance that can change states through physical processes such as evaporation and condensation, without altering its chemical composition.
Step-by-step explanation:
The question seeks an example of a substance that can change states. Among the options provided, water is a classic example of a substance that can undergo phase changes. When water is heated, it can turn into steam, which is the gas phase of water (physical change). Conversely, when steam cools down, it condenses back into liquid water, once again demonstrating a change in state without altering the chemical composition of the substance. This exemplifies a physical change since the substance remains water throughout the transformation between solid, liquid, and gas.