Exam-style question
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In a cooling curve, what does a decrease in the slope indicate about the rate of cooling?.
- A.The rate of cooling is increasing.
- B.The rate of cooling is constant.
- C.The rate of cooling is decreasing.
- D.The substance is at thermal equilibrium.
Model answer
What a good answer should say
- The rate of cooling is decreasing.
Explanation
Why this works
The evidence of a decreasing slope in a cooling curve indicates that the temperature of the substance is dropping at a slower rate over time. This shows that as the substance cools, the rate of thermal energy loss diminishes.
The implication is that the temperature difference between the substance and its surroundings is becoming smaller. Therefore, we conclude that the rate of cooling is decreasing.
Common mistake
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