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Pearson Edexcel International GCSE (9–1) · CHEMISTRY · Section

Relative atomic mass

19 practice questions

Start practising (19 questions)

Practice questions

11–19 of 19

  1. Question 11

    3 marks · Normal

    Bromine consists of two isotopes: and . The percentage abundances are 51% and 49% respectively. Calculate the relative atomic mass of bromine. Give your answer to 1 decimal place.

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  2. Question 12

    3 marks · Normal

    Chlorine exists mainly as two isotopes, and . The Periodic Table gives chlorine a relative atomic mass of 35.5.

    Explain why this value is not a whole number. Your answer should refer to isotopes and how the value is calculated.

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  3. Question 13

    4 marks · Normal

    The table shows the abundances of three isotopes of element X.

    IsotopeRelative Mass% Abundance
    X-101020
    X-111150
    X-121230
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  4. Question 14

    1 mark · Normal

    Which statement correctly describes all isotopes of an element?

    1. A.They have the same mass number but different atomic numbers.
    2. B.They have the same number of protons but different numbers of neutrons.
    3. C.They have different chemical properties.
    4. D.They contain the same number of neutrons.
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  5. Question 15

    2 marks · Normal

    An atom of sodium-23 () has how many neutrons?

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  6. Question 16

    4 marks · Normal

    Consider two isotopes of carbon: and .

    (a)

    State the number of protons and neutrons in .

    [1 mark]
    (b)

    State the number of protons and neutrons in .

    [1 mark]
    (c)

    Explain why and are considered isotopes of the same element.

    [1 mark]
    (d)

    Describe one way in which the two isotopes differ.

    [1 mark]
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  7. Question 17

    2 marks · Hard

    A sample of element Q contains 10% of isotope Q-40 and 90% of isotope Q-42.

    Calculate the relative atomic mass of Q. Give your answer to one decimal place.

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  8. Question 18

    5 marks · Hard

    (a)

    Describe what isotopes are.

    [1 mark]
    (b)

    The element magnesium has isotopes with mass numbers 24, 25, and 26. Give the number of protons and neutrons in each of these isotopes.

    IsotopeNumber of protonsNumber of neutrons
    ^24Mg
    ^25Mg
    ^26Mg
    [3 marks]
    (c)

    Explain why magnesium-24, magnesium-25, and magnesium-26 all have the same chemical properties.

    [1 mark]
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  9. Question 19

    2 marks · Hard

    The element X has two stable isotopes: X-64 (mass = 64, abundance = 73%) and X-66 (mass = 66, abundance = 27%).

    Calculate the relative atomic mass of X. Give your answer to one decimal place.

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