Which observation most likely indicates that only a chemical change has taken place?(1 point)
Responses
A reaction occurs.
A reaction occurs.
The shape changes.
The shape changes.
The change cannot be reversed.
The change cannot be reversed.
States of matter changes.
States of matter changes.
Use the table of observed changes to answer the question.
Change # Reacts with another substance? Temperature change? Gas, sound, or light produced? New substance formed?
1 yes yes yes yes
2 no yes yes no
3 yes yes yes yes
4 no no no no
Which changes shown in the table are physical changes?
(1 point)
Responses
1 and 4
1 and 4
1 and 2
1 and 2
2 and 4
2 and 4
2 and 3
2 and 4
Why is it a physical change to freeze water?(1 point)
Responses
The new and original substances are different.
The new and original substances are different.
Heat is released during the process.
Heat is released during the process.
A temperature change occurs.
A temperature change occurs.
Only a phase change occurs.
Only a phase change occurs.
Which option is an example of a chemical change?(1 point)
Responses
chopping vegetables
chopping vegetables
stretching a rubber band
stretching a rubber band
folding paper
folding paper
burning wood
burning wood
burning wood
BAAA
The observation that most likely indicates that only a chemical change has taken place is when the change cannot be reversed. This is because chemical changes involve the formation of new substances with different chemical properties, and these changes are typically irreversible.
To determine if a change is a chemical change or a physical change, you can use the following criteria:
1. Observe if a reaction occurs: Chemical changes involve the formation of new substances through a chemical reaction. This can include the release or absorption of energy, the production of gas, or the formation of a precipitate. If a reaction occurs, it suggests a chemical change.
2. Assess if the shape changes: Changes in shape or size usually indicate a physical change rather than a chemical change. Physical changes involve alterations in the state or appearance of a substance, but do not result in the formation of new substances.
3. Consider reversibility: Physical changes can usually be reversed by simple means, such as melting or freezing. On the other hand, chemical changes typically produce new substances that cannot be easily converted back to their original form.
4. Note changes in states of matter: Changes in states, such as melting, boiling, or condensing, are typically physical changes. These changes involve alterations in the arrangement or movement of particles, but not in their chemical composition.
In summary, if the change cannot be reversed, it is likely that only a chemical change has taken place. It is important to consider multiple observations and characteristics when determining whether a change is chemical or physical.