Freezing water is considered a physical change because it primarily involves a change in the state of matter from liquid to solid without altering the chemical composition of the water itself. Here’s a breakdown of your options:
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Only a phase change occurs: This is the most accurate statement. Freezing water is a phase change from liquid to solid (ice). The molecular structure rearranges, but the chemical identity of water remains unchanged (it is still H₂O).
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A temperature change occurs: While it is true that the temperature decreases as water freezes, this is not the primary reason it is classified as a physical change. Temperature change can occur in both physical and chemical changes.
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Heat is released during the process: This statement is also true, as freezing is an exothermic process where heat is released when water changes to ice. However, like the previous option, this does not define it solely as a physical change.
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The new and original substances are different: This statement is incorrect in the context of freezing water. After freezing, the substance is still water, just in a different physical state (ice).
In summary, the best option that explains why freezing water is a physical change is "Only a phase change occurs."