Multiple Choice
Which of the following statements about the melting temperature of potassium chloride (KCl) is correct?
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1. Intro to General Chemistry
Chemical Properties
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Which of the following is an example of a chemical reaction?
A
Water freezing to form ice
B
Salt dissolving in water
C
Iron rusting when exposed to air
D
Breaking a glass into pieces
Verified step by step guidance1
Understand the definition of a chemical reaction: it involves the rearrangement of atoms to form new substances with different chemical properties.
Analyze each option to see if new substances are formed: Water freezing to form ice is a physical change because the molecular structure of H\_2O remains the same.
Salt dissolving in water is also a physical change since the salt dissociates into ions but no new chemical substances are created.
Iron rusting when exposed to air is a chemical reaction because iron reacts with oxygen and moisture to form a new compound, iron oxide (rust).
Breaking a glass into pieces is a physical change because the glass is only physically broken, not chemically altered.
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