Final answer:
A physical change may involve a change in shape, phase, or volume, without altering the chemical composition of the substance. No new substances are formed, as physical changes are about the arrangement and physical properties, not the chemical identity.
Step-by-step explanation:
A physical change may involve changes that can be seen or felt, such as a change in shape, phase, or volume. These changes include alterations in physical properties like size or phase transition from solid to liquid or gas, but do not result in different substances being present. A physical change does not affect the chemical composition of the substance, meaning no new compounds are formed, and no bonds are broken or made. Examples of physical changes are melting of ice, freezing of water, or dissolving salt in water.
When answering the provided question:
- A change in shape (a) is a physical change.
- A change in phase (b) is a physical change, such as water turning to ice or steam.
- A change in volume (c) can be a physical change, for instance when gas expands upon heating.
- A change in color can be tricky because it may indicate a chemical change in certain contexts; however, if color change occurs without altering the chemical structure, such as a change in an object's appearance due to different lighting, it could be considered a physical change.
The key aspect of a physical change is that the identity of the substance remains the same despite these alterations.