Milady Esthetics State Board Practice Test

What type of change results in a substance's state changing without altering its chemical composition?

1. Chemical change

2. Physical change

3. Biological change

4. Thermal change

The correct answer is: Physical change

A physical change is characterized by a change in the state of a substance that does not affect its chemical composition. This type of change may involve transformations such as melting, freezing, evaporating, condensing, or dissolving. During a physical change, the molecules of the substance remain unchanged in their chemical structure; only their arrangement or state has altered. For example, when ice melts into water, it changes from solid to liquid, but the chemical composition of H₂O remains the same. In contrast, a chemical change involves a transformation that alters the composition of substances, resulting in new materials with different chemical properties. Biological changes would relate to processes that involve living organisms and might also change the chemical composition. Thermal change often refers to changes in temperature but is not specific to the type of change in state being described here. Therefore, the correct answer focuses on the properties and nature of physical changes, making it the appropriate choice.