GK QUESTION#3364
In the usual paper-cup demonstration, why can the water-wetted part of the cup resist catching fire while liquid water remains in it?
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Answer
B. The water absorbs most of the heat and keeps the paper below its ignition temperature
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Explanation
Water absorbs heat from the paper in contact with it. While liquid water remains, the wetted paper stays near the water temperature and can remain below its ignition temperature. This does not make paper permanently non-flammable: dry areas or an emptied cup can still burn.