Why does a paper cup not burn when filled with water and heated?
Show answer & explanation
Correct answer: B
Explanation
Correct Answer: Option 2: Water absorbs heat, preventing the paper from reaching its ignition temperature.
Explanation:
When a paper cup filled with water is heated, the heat transferred immediately from the paper to the water. Water is a good heat absorber, so it prevents the paper's temperature from rising to its ignition temperature. The paper doesn't burn until all the water inside the cup has boiled away.
Additional Facts:
Ignition temperature: The lowest temperature at which a substance catches fire.
Heat transfer: Here, heat flows from the paper to the water by conduction.
Boiling point of water: The boiling point of water is 100°C, which is significantly lower than the ignition temperature of paper.
Possible Questions for the Upcoming Exam:
What is the lowest temperature at which a substance begins to burn? (Answer: Ignition temperature).
By what process is heat transferred when heating water in a paper cup? (Answer: Conduction).
If the paper cup contained oil instead of water, would the results be different? (Answer: Yes, because different liquids have different specific heat capacities).