What defines a physical change?

A physical change is defined as a transformation that alters the form or appearance of a substance without changing its chemical composition. This means that the molecular structure of the substance remains unchanged and no new substances are created. Examples of physical changes include melting ice into water, dissolving sugar in water, and breaking a glass. In these instances, the material retains its original properties, and if the process is reversed, the original substance can be recovered.

The other options pertain to different concepts in chemistry. A change in chemical composition refers to a chemical change, where new substances with different properties are formed. Changes in matter's mass can occur in both physical and chemical changes, but mass alone does not define the nature of the change. Energy release is typically associated with chemical changes, especially exothermic reactions, but does not relate directly to physical changes.