객관식
Which of the following is a sign that a chemical change has occurred?
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1. Intro to General Chemistry
Physical & Chemical Changes
객관식
When two liquids are mixed and bubbles form, what type of change has most likely occurred?
A
A chemical change, because the temperature always increases when bubbles form.
B
A chemical change, because a gas is produced indicating a new substance is formed.
C
A physical change, because no new substance is formed when bubbles appear.
D
A physical change, because mixing liquids always produces bubbles.
검증된 단계별 안내1
Understand the difference between physical and chemical changes: A physical change affects the form of a substance but not its chemical composition, while a chemical change results in the formation of one or more new substances.
Recognize that the formation of bubbles when two liquids are mixed usually indicates the production of a gas.
Recall that the production of a gas is a strong sign that a chemical reaction has occurred, because gases are often new substances formed during chemical changes.
Note that temperature changes can accompany chemical reactions but are not definitive proof on their own; the key indicator here is the formation of a gas (bubbles).
Conclude that the appearance of bubbles when mixing two liquids most likely indicates a chemical change, as it shows a new substance (gas) is being produced.
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