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Relative atomic mass from isotope abundances

10th grade (Year 11 in England) · 16 questions · Common Core: NGSS.HS-PS1-1, NGSS.SEP 5 · England: GCSE Combined Science: Atomic structure (relative atomic mass)

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  1. Question 1

    Why is the relative atomic mass of chlorine 35.5 and not a whole number?

    • A. Electrons add 0.5
    • B. It is an average of its isotopes, weighted by abundance
    • C. Chlorine atoms have half a neutron
    • D. It is measured badly

  2. Question 2

    An element has two isotopes: mass 46 (40 %) and mass 48 (60 %). What is its relative atomic mass? Give 1 decimal place.

    Answer

  3. Question 3

    Natural gallium contains 60 % of mass 69 and 40 % of mass 71. Calculate its relative atomic mass to 1 decimal place.

    Answer

  4. Question 4

    Why is the relative atomic mass of chlorine 35.5 and not a whole number?

    • A. It is an average of its isotopes, weighted by abundance
    • B. Chlorine atoms have half a neutron
    • C. It is measured badly
    • D. Electrons add 0.5

  5. Question 5

    An element has two isotopes: mass 78 (20 %) and mass 80 (80 %). What is its relative atomic mass? Give 1 decimal place.

    Answer

  6. Question 6

    Natural boron contains 20 % of mass 10 and 80 % of mass 11. Calculate its relative atomic mass to 1 decimal place.

    Answer

  7. Question 7

    What are isotopes?

    • A. atoms of different elements with the same mass
    • B. ions with different charges
    • C. atoms with different numbers of protons
    • D. atoms of the same element with different numbers of neutrons

  8. Question 8

    An element has two isotopes: mass 60 (60 %) and mass 62 (40 %). What is its relative atomic mass? Give 1 decimal place.

    Answer

  9. Question 9

    Natural copper contains 69 % of mass 63 and 31 % of mass 65. Calculate its relative atomic mass to 1 decimal place.

    Answer

  10. Question 10

    Carbon-12 and carbon-14 are isotopes. How many neutrons does carbon-14 have? (Carbon has 6 protons.)

    • A. 8
    • B. 6
    • C. 14
    • D. 12

  11. Question 11

    An element has two isotopes: mass 62 (10 %) and mass 64 (90 %). What is its relative atomic mass? Give 1 decimal place.

    Answer

  12. Question 12

    Natural chlorine contains 75 % of mass 35 and 25 % of mass 37. Calculate its relative atomic mass to 1 decimal place.

    Answer

  13. Question 13

    Carbon-12 and carbon-14 are isotopes. How many neutrons does carbon-14 have? (Carbon has 6 protons.)

    • A. 14
    • B. 8
    • C. 12
    • D. 6

  14. Question 14

    An element has two isotopes: mass 40 (60 %) and mass 42 (40 %). What is its relative atomic mass? Give 1 decimal place.

    Answer

  15. Question 15

    Natural gallium contains 60 % of mass 69 and 40 % of mass 71. Calculate its relative atomic mass to 1 decimal place.

    Answer

  16. Question 16

    Why is the relative atomic mass of chlorine 35.5 and not a whole number?

    • A. It is an average of its isotopes, weighted by abundance
    • B. It is measured badly
    • C. Electrons add 0.5
    • D. Chlorine atoms have half a neutron

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  1. It is an average of its isotopes, weighted by abundance
  2. 47.2
  3. 69.8
  4. It is an average of its isotopes, weighted by abundance
  5. 79.6
  6. 10.8
  7. atoms of the same element with different numbers of neutrons
  8. 60.8
  9. 63.6
  10. 8
  11. 63.8
  12. 35.5
  13. 8
  14. 40.8
  15. 69.8
  16. It is an average of its isotopes, weighted by abundance