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NEET Sample Paper NEET Sample Test Paper-82

  • question_answer
    Boron exists in nature as two naturally occurring isotopes having atomic weights 10.01 and 11.01. Atomic weight of naturally occurring boron is 10.01. The relative isotopic abundance of isotopes are

    A) \[70\,%\text{ }and\text{ }30\,%\]           

    B) \[85\,% and 15\,%\]

    C) \[19.8\,% and 80.2\,%\]

    D) \[90\,% and 10\,%\]

    Correct Answer: C

    Solution :

    Let sample of boron having atomic mass 10.01 is \[x\,%\]. Sample of boron having atomic mass 11.01 is \[\] \[\left( 100 -x \right)%\] Average atomic weight \[=\,\,\frac{\operatorname{x}\,\,\times  10.01 + \left( 100-x \right)\times 11.01}{100}\] \[x=19.80%\] \[\therefore 100-x=100-19.8=80.20%\]


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