What type of change occurs when the chemical composition of a substance remains the same?

A physical change occurs when the chemical composition of a substance remains the same. This type of change affects the physical properties of the substance, such as its state (solid, liquid, gas), shape, size, or appearance, but does not alter the substance's chemical structure. Common examples of physical changes include melting ice into water, boiling water into steam, or breaking a glass. Despite these alterations in form or appearance, the underlying chemical identity of the substance remains intact.

In contrast, a chemical change involves a transformation that results in the formation of one or more new substances with different chemical properties and compositions, exemplified by processes like rusting iron or burning wood. Mechanical change is not typically a term used in chemistry; it might suggest physical alterations due to physical forces. Biochemical change refers to processes that occur in living organisms and often involve chemical reactions but do not fit the definition given in the question. Therefore, since the core requirement is that the chemical composition remains unchanged, the identification of the correct response as physical change is valid.