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8th Class Science Combustion and Flame Question Bank Combustion and Flame HOTS Objective Problems

  • question_answer
    Rajesh made two paper cups I and II by folding a sheet of paper. He pours 50 mL water in cup II, and heats both cups separately with the help of a candle (as shown in the figure). Rajesh observes that while one paper cup burns readily, the other does not burn. He observed that paper cup ____i____ does not burn since its ignition temperature was ______ii______ while heating.
    The information in which alternative completes the given statement?

    A)  i-I, ii-reached  

    B)  i-II, ii-reached

    C)  i-I, ii-not reached     

    D)  i-I, ii-not reached

    Correct Answer: D

    Solution :

      The ignition temperature of a substance is the minimum temperature at which it starts burning. A substance does not catch fire as long as its temperature is lower than its ignition temperature. In the presence of water, the ignition temperature of paper cup II is not reached. This is because water absorbs all heat and gets converted into water vapours. As a result, paper cup II does not burn. The correct answer is D.


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