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

  • question_answer
    Ravi takes three substances X, Y, and Z. On heating these substances he observes that they bum at different temperatures. He finds out that X catches fire on little heating, while Y and Z do not catch fire. On further heating of Y and Z, he observes that Y catches fire, while Z does not. The correct arrangement of X, Y, and Z in order of their increasing ignition temperatures is

    A)  \[X<Y<Z\]          

    B)  \[Z<Y<X\]

    C)  \[Z<X<Y\]                          

    D)  \[Y<X<Z\]

    Correct Answer: A

    Solution :

      The ignition temperature of a substance is the minimum temperature at which a substance catches fire or starts burning. While X burns on little heating, Y and Z do not burn. This shows that the ignition temperature of X is lower than that of Y and Z. On further heating of Y and Z, it was found that Y had caught fire at a temperature that was lower than Z (as the latter does not start burning). Thus, it can be concluded that the ignition temperature of Y is lower than that of Z. Hence, the correct arrangement of the substances (X, Y, and Z) in order of their increasing ignition temperatures is\[X<Y<Z\]. The correct answer is A.     


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