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9th Class Science Atoms and Molecules Question Bank Atoms and Molecules

  • question_answer
    Two samples X and Y of a pure substance obtained by two different methods contain elements P and Q. Substance X has a mass of 2.25 g and contains 0.90 g of 0. Substance Y is made up of 60% P and 40% 0 by weight. This is an illustration of

    A) Law of multiple proportions

    B) Law of constant proportions

    C) Law of reciprocal proportions

    D) Gay-Lussac's law of combining volumes.

    Correct Answer: B

    Solution :

    Mass of X= 2.25 g Mass of Q = 0.90 g Thus, mass of P = 2.25 - 0.90 = 1.35 g Ratio of masses of P and Q in sample 'X' = 1.35 : 0.90 i.e.; 1.5 :1 Ratio of masses of P and Q in sample 'Y' = 60 : 40 i.e.; 1.5 :1 As the ratio of the masses of P and Q in two samples 'X' and 'Y' is constant i.e., 1.5 : 1 so, this is an illustration of 'law of constant proportions'.


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