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

  • question_answer
    The ignition temperatures of four substances, P, Q, R, and S, are \[{{125}^{o}}C\], \[{{270}^{o}}C\], \[{{155}^{o}}C\], and \[{{310}^{o}}C\] respectively. Which of the following pairs of substances catches fire at \[{{250}^{o}}C\]?

    A)  Q and S                               

    B)  P and R

    C)  R and S                               

    D)  P and Q

    Correct Answer: B

    Solution :

      The lowest temperature at which a substance catches fire is called its ignition temperature. A substance burns only when the temperature of the substance is higher than its ignition temperature. The ignition temperatures of P and R are lower than\[250{}^\circ \]. Therefore, P and R will catch fire at\[250{}^\circ C\].The correct answer is B.


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