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BCECE Engineering BCECE Engineering Solved Paper-2001

  • question_answer
    The element chlorine consists of a mixture of \[\text{75}\text{.53 }\!\!%\!\!\text{ }\,{{\,}_{\text{17}}}\text{C}{{\text{l}}^{\text{35}}}\]and \[24.47%\,{{\,}_{17}}C{{l}^{37}}\]having a mass of 34.97 amu and 36.95 amu, respectively. The atomic weight of chloride is:

    A) 35.25                     

    B)        35.45

    C) 36.25                     

    D)        36.45

    Correct Answer: B

    Solution :

    Key Idea: At. wt. of chlorine \[\text{=}\,\frac{\text{Abundance}\,\text{ }\!\!\times\!\!\text{ }\,\text{mass}\,\text{+}\,\text{Adundance}\,\text{ }\!\!\times\!\!\text{ }\,\text{mass}}{\text{100}}\] Given, abundance of \[\text{C}{{\text{l}}^{\text{35}}}\]isotope \[=75.53%\] Mass of \[C{{l}^{35}}\]isotope \[=34.97\] Abundance of \[C{{l}^{37}}\]isotope \[=24.47%\] Mass of \[C{{l}^{37}}\]isotope \[=36.95\] \[\therefore \] At. wt. of chlorine \[=\frac{34.97\times 75.53+24.47\times 36.95}{100}\] \[=\frac{3545.45}{100}\] \[=35.45\]


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