Physical versus chemical change quick check which observation most likely indicates that only a chemical change has taken place to change cannot be reversed a reaction occurs a shape changes states of matter change
The observation that most likely indicates that only a chemical change has taken place and it cannot be reversed is "a reaction occurs." This indicates that a chemical reaction has occurred, resulting in the formation of new substances with different chemical properties.
The observation that most likely indicates that only a chemical change has taken place and cannot be reversed is "a reaction occurs." When a chemical change occurs, it usually involves the formation of new substances with different chemical properties. These changes are often irreversible, meaning the original substances cannot be regained through simple physical means. In contrast, a shape change or a change in states of matter can generally be reversed without any chemical reactions occurring.
The observation that most likely indicates that only a chemical change has taken place, which cannot be reversed, is when a reaction occurs.
To determine whether a physical or chemical change has occurred, you can evaluate the nature of the change and its reversibility. Here's how you can analyze each observation:
1. A reaction occurs: If you witness a chemical reaction, such as two substances combining to form a new substance or the breakdown of a substance into different components, it suggests a chemical change. Chemical changes typically involve the rearrangement of atoms and the formation of new chemical bonds. Unlike physical changes, chemical changes are often not reversible, meaning the original substances cannot be easily recovered.
2. A shape changes: A change in shape is usually indicative of a physical change. Physical changes involve alterations in the physical properties of a substance such as size, shape, or state, without any changes to its chemical composition. These changes are typically reversible, and the original substance can usually be restored.
3. States of matter change: When the state of matter changes (such as solid to liquid, liquid to gas, or vice versa), it indicates a physical change. This change is caused by altering the arrangement and motion of the particles without affecting their identities. Like other physical changes, changes in states of matter are usually reversible.
In summary, the observation of a reaction occurring is the strongest indicator that only a chemical change has taken place.