Which of the following happens during a chemical change but does not happen during a physical change?
The state of the substance changes.
The appearance of a substance changes, but it is still the same substance.
Atoms of one or more substances rearrange into a new substance.
The mass of the substance changes.
Atoms of one or more substances rearrange into a new substance.
The correct answer is: Atoms of one or more substances rearrange into a new substance.
During a chemical change, such as a chemical reaction, the arrangement of atoms in the substances involved is altered, resulting in the formation of one or more new substances. This rearrangement of atoms leads to the creation of different chemical bonds and the development of different properties. In contrast, physical changes involve alterations in the state or appearance of a substance, but the fundamental composition and arrangement of its atoms are not changed.
To identify which of the given options happens during a chemical change but not during a physical change, let's examine each option and determine the differences between chemical and physical changes.
1. The state of the substance changes: This can happen during both chemical and physical changes. For example, when water freezes and turns into ice, or when it boils and turns into steam. Therefore, this option does not exclusively occur during a chemical change.
2. The appearance of a substance changes, but it is still the same substance: This is commonly observed in physical changes. For instance, when a solid is ground into a powder, or when water evaporates into the air. Thus, this option does not solely indicate a chemical change.
3. Atoms of one or more substances rearrange into a new substance: This is a characteristic feature of a chemical change. During a chemical reaction, molecules break apart, and their atoms rearrange to form new substances with different properties. Thus, this option only occurs in a chemical change.
4. The mass of the substance changes: This is also observed during both chemical and physical changes. However, in a physical change, the mass remains the same since no new substances are formed or destroyed. In contrast, during a chemical change, the mass may change due to the formation of new substances or the release of gases. Therefore, this option can occur in both types of changes.
In conclusion, option 3 - "Atoms of one or more substances rearrange into a new substance" happens exclusively during a chemical change and does not occur during a physical change.