Which observation most likely indicates that only a chemical change has taken place?(1 point)
Responses
The change cannot be reversed.
The change cannot be reversed.
A reaction occurs.
A reaction occurs.
States of matter changes.
States of matter changes.
The shape changes.
A reaction occurs.
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
2 and 3
2 and 3
1 and 4
1 and 4
1 and 2
1 and 2
2 and 4
2 and 4
2 and 4
Why is it a physical change to freeze water?(1 point)
Responses
A temperature change occurs.
A temperature change occurs.
Only a phase change occurs.
Only a phase change occurs.
Heat is released during the process.
Heat is released during the process.
The new and original substances are different.
Only a phase change occurs.
Which option is an example of a chemical change?(1 point)
Responses
stretching a rubber band
stretching a rubber band
burning wood
burning wood
chopping vegetables
chopping vegetables
folding paper
folding paper
Burning wood
tysm! bye
To determine which observation most likely indicates that only a chemical change has taken place, we need to understand the difference between chemical changes and physical changes.
In a chemical change, new substances are formed with different chemical properties. This typically involves a chemical reaction where one or more substances are converted into different substances.
In a physical change, on the other hand, the composition and chemical properties of the substances remain the same, but there may be changes in states of matter, shape, size, or form.
Now, let's analyze the given observations:
1. "The change cannot be reversed."
This statement alone doesn't provide enough information to determine whether a chemical change has occurred or not. Both chemical and physical changes can be irreversible, so it's not a definitive indicator.
2. "A reaction occurs."
This observation suggests that a chemical change has likely taken place since reactions between different substances often involve the formation of new substances with different properties.
3. "States of matter change."
Changes in states of matter, such as solid to liquid or liquid to gas, are typically associated with physical changes rather than chemical changes. This observation indicates a physical change, not necessarily a chemical change.
4. "The shape changes."
Similar to the previous observation, changes in shape generally indicate physical changes rather than chemical changes. The rearrangement or deformation of particles within a substance does not necessarily involve the formation of new substances.
Based on the explanations provided, the observation "A reaction occurs" is the one that most likely indicates that only a chemical change has taken place.