Isotopes Practice Quiz

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About This Quiz

A 5-question practice quiz for the topic on Isotopes at www. Thechemwhiz. Piczo. Com
Note: you'll need a calculator.

Isotopes Practice Quiz - Quiz

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  • 2. 

    Magnesium has three of it's own isotopes.  78.7% is Magnesium-24. 10.13% is Magnesium-25. 11.17% is Magnesium-26. Calculate the relative atomic mass of Magnesium, to two decimal places.

    Explanation
    (78.7 x 24) + (10.13 x 25) + (11.17 x 26)
    /100
    = 24.32

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  • 3. 

    Calculator time!  19.9% of all Boron atoms are Boron-10. 80.1% are Boron-11. Calculate the approximated relative atomic mass of Boron, to one decimal place.

    Explanation
    (19.9 x 10) + (80.1 x 11)
    /100
    = 10.8

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  • 4. 

    In an isotope, which part of the atom changes?

    • Protons

    • Neutrons

    • Electrons

    Correct Answer
    A. Neutrons
  • 5. 

    Element occurs naturally in the environment. Scientists have found 612 atoms of A-15, 829 atoms of A-16, and 244 atoms of A-17. Calculate the relative atomic mass of the element to two decimal places.

    Correct Answer
    15.78
    Explanation
    First, you have to get the percentages of all these isotopes of Element A. Add them all up together.
    612+829+244 = 1685

    Then, find the percentages of each - use the formula ([Number of Atoms/Total in the Sample] x 100)
    ([612/1685] x 100) = 36.32% of A-15.
    ([829/1685] x 100) = 49.20% of A-16
    ([244/1685] x 100) = 14.48% of A-17.

    Now do what you've always done - multiply the percentages by the masses, add them all up, and divide by 100.
    (36.32 x 15) + (49.20 x 16) + (14.48 x 17)
    /100
    = 15.78

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Quiz Review Timeline (Updated): Mar 21, 2022 +

Our quizzes are rigorously reviewed, monitored and continuously updated by our expert board to maintain accuracy, relevance, and timeliness.

  • Current Version
  • Mar 21, 2022
    Quiz Edited by
    ProProfs Editorial Team
  • Nov 06, 2011
    Quiz Created by
    Superoxideion01
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