Final answer:
Physical changes of matter are changes that do not create new substances, but may alter a substance's appearance or state while preserving its molecular structure. For example, melting ice changes its form from solid to liquid but remains H₂O.
Step-by-step explanation:
Physical changes of matter refer to changes that do not create new substances. Instead, they involve alterations in the appearance or form of a substance without changing its molecular structure. Examples of physical changes include melting, evaporating, and sublimation.
When ice (solid water) melts, it becomes liquid water, and when that water evaporates, it becomes water vapor (gas), but in all these changes, the molecular structure of H₂O remains the same. Hence, during a physical change, while the arrangement of particles may change, the mass, number of atoms, and number of molecules stay consistent.
A physical change is a change in which the appearance or form of a substance is altered, but the molecular structure remains the same. Physical changes do not result in the formation of new substances or molecules. Examples of physical changes include melting ice, evaporating water, and dissolving a substance in another.
Answering the student's question, physical changes are C. changes that do not make new substances.