Skip to content

When Helping Means Winning contest

Ask a school-related question in the Help Zone and you could win one of three $500 scholarships. See the details

See the details

Help Zone

Student Question

Secondary IV • 8d

How do I solve this question? Step by step please.



{t c="richEditor.description.title"} {t c="richEditor.description.paragraphMenu"} {t c="richEditor.description.inlineMenu"} {t c="richEditor.description.embed"}

Explanations (1)

  • Explanation from Alloprof

    Explanation from Alloprof

    This Explanation was submitted by a member of the Alloprof team.

    Team Alloprof • 8d

    Good morning UnusualKamino2636.

    Welcome in the Zone!

    The mass number of an atom (A) is equal to the sum of the number of protons (Z) and neutrons in the nucleus. So, if an atom contains 20 protons and 40 neutrons, his mass number is then 60 (20+40).

    When it comes to writing the isotope, you have to use this way ...

    Capture d’écran, le 2023-03-13 à 11.12.49.png

    Since the atomic number (or number of protons) is 20, your only choice is Ca, because Mg has an atomic number of 12.

    I hope theses explanations helped you to understand how to to write isotopes.

    Thank you for your confidence in Alloprof. Have a nice day.