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

  • question_answer
    Geeta took four combustible substances I, II, II, and IV. She found out that the ignition temperatures of I, n, III, and IV is\[{{233}^{o}}C\], \[{{473}^{o}}C,\] \[{{210}^{o}}C,\]and \[{{170}^{o}}C,\] respectively. She heats all the substances to \[{{190}^{o}}C,\]. Among the given substances, which substance will catch fire when heat is supplied to it?

    A)  I                                             

    B)  II

    C)  III                                          

    D)  IV

    Correct Answer: D

    Solution :

      Different substances catch fire at different temperatures. The ignition temperature of a substance is the lowest temperature at which a substance catches fire or starts burning. A substance cannot catch fire as longs as its temperature is lower than its ignition temperature. When substances I, II, III, and IV are heated to\[190{}^\circ C\]by Geeta, only the ignition temperature of substance IV is reached. Thus, only IV will catch fire. The correct answer is D.


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