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What does the law of conservation of energy state about a chemical or physical change?
AEnergy is used up as the change proceeds
BEnergy is created whenever a fuel burns up
CEnergy is destroyed when a body cools down
DEnergy changes form but is neither made nor lost
Answer & Solution
Correct answer: D. Energy changes form but is neither made nor lost
1. All the energy present before a change still exists in some form afterwards.
2. Only the form changes, for example chemical energy becoming mechanical energy in an engine.
3. So energy can be neither created nor destroyed during the change.
4. This statement is also one version of the first law of thermodynamics.
5. Saying energy is used up confuses change of form with loss of energy.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 5 "Thermochemistry", section 5.1 Energy Basics_
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