Which observation most likely indicates that only a chemical change has taken place?(1 point) Responses The shape changes. The shape changes. States of matter changes. States of matter changes. A reaction occurs. A reaction occurs. The change cannot be reversed.
A reaction occurs
The observation that most likely indicates that only a chemical change has taken place is when a reaction occurs.
The observation that most likely indicates that only a chemical change has taken place is "A reaction occurs." Here's how you can identify this:
When a chemical change occurs, substances combine, break apart, or rearrange to form new substances with different chemical properties. This process is known as a chemical reaction. Some signs of a chemical reaction include the formation of a gas, a change in color, the release or absorption of heat or light, and the production of a precipitate (a solid formed from the reaction of two liquids).
In the given options, "A reaction occurs" implies that some sort of chemical reaction has taken place, indicating a chemical change. The other options, such as "The shape changes" and "States of matter changes," can also indicate a change, but these changes can occur through physical means (without involving a reaction) and may not necessarily be signs of a chemical change. "The change cannot be reversed" does not necessarily suggest a chemical change either, as both physical and chemical changes can be irreversible.
Therefore, the observation "A reaction occurs" is the most likely indication that only a chemical change has taken place.