How are chemical changes different from physical changes? (1 point)
O They involve heat.
O They include shifts in the phase of matter.
O They are reversible.
They form new substances.
The correct answer is: They form new substances.
Chemical changes are different from physical changes because they form new substances. While physical changes involve shifts in the phase of matter, such as melting, boiling, or freezing, chemical changes result in the formation of entirely new substances with different chemical properties. Chemical reactions typically involve the breaking and forming of chemical bonds. Additionally, chemical changes are often accompanied by the release or absorption of heat, but this is not a defining characteristic of chemical changes. Furthermore, physical changes can be reversible, meaning that the original substance can be obtained again after the change, while chemical changes are usually not reversible.
The correct answer is: They form new substances.
Chemical changes are different from physical changes because they involve a chemical reaction, where new substances are formed with different properties than the original substances. Physical changes, on the other hand, do not involve a change in the composition of the substances and only affect their physical properties, such as shape, size, or state of matter.
To understand the difference between chemical and physical changes, you need to know that chemical changes occur at the molecular level, involving the rearrangement of atoms to form new chemical bonds. This process leads to the formation of entirely different substances with distinct properties. In contrast, physical changes do not change the chemical composition of a substance; they only alter its physical state or appearance. For example, melting a solid to form a liquid is a physical change as it only affects the state of matter, while burning a piece of paper is a chemical change as it produces new substances such as ash and smoke.
So, to identify whether a change is chemical or physical, you can observe if there is a formation of new substances. If new substances are formed, it indicates a chemical change.