Which observation most likely indicates that only a chemical change has taken place?(1 point) Responses States of matter changes. States of matter changes. A reaction occurs. A reaction occurs. The shape changes. The shape changes. The change cannot be reversed
A reaction occurs.
The observation that indicates that only a chemical change has taken place is "A reaction occurs." Chemical changes involve the formation or breaking of chemical bonds, resulting in the creation of new substances.
The observation that most likely indicates that only a chemical change has taken place is "A reaction occurs." This is because a chemical change involves the formation of new substances with different properties through the rearrangement of atoms and molecules. When a reaction occurs, it implies that there has been a chemical transformation.
To determine whether a chemical change has occurred, you can look for other indicators as well. One such indicator is when the states of matter change. For example, if a liquid evaporates and becomes a gas, or if a solid melts and becomes a liquid, these changes in state indicate a physical change rather than a chemical change.
Another potential indication of a chemical change is when the shape changes. However, this alone may not be enough evidence, as shape changes can also be the result of physical processes. The key difference is that a shape change due to a chemical change is often accompanied by the formation of new substances.
Lastly, if the change cannot be reversed, it suggests a chemical change. Physical changes can usually be reversed, such as by melting ice to obtain water. In contrast, chemical changes often lead to the formation of new substances that cannot be easily reverted back to their original form.
In summary, while there are several observations that can indicate a chemical change, the most distinct indicator is the occurrence of a reaction, which signifies the formation of new substances through the rearrangement of atoms and molecules.