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Atomic Number and Mass Number MCQs

Practice Atomic Number and Mass Number multiple-choice questions from Atomic Foundations of Matter (Class 9 Science) - tap an answer for instant feedback and a step-by-step solution. Practice the full set free on the RankByte app.

Atomic Number and Mass NumberQuiz - Solve & Score

  1. Q1. Which quantity stays the same for all isotopes of chlorine?

    • A.the atomic number (number of protons)
    • B.the mass number
    • C.the number of neutrons
    • D.the total atomic mass

    Answer: A. the atomic number (number of protons)

  2. Q2. Why is the mass number, and not the precise atomic mass, used when writing nuclear symbols?

    • A.it is a simple whole-number count of nucleons
    • B.it equals the number of electrons
    • C.it changes with the atom's charge
    • D.it is always larger than the real mass

    Answer: A. it is a simple whole-number count of nucleons

  3. Q3. Why do isotopes of an element have the same atomic number but different mass numbers?

    • A.they have the same number of protons but different numbers of neutrons
    • B.they have different numbers of protons
    • C.they have different numbers of electrons
    • D.they have no neutrons

    Answer: A. they have the same number of protons but different numbers of neutrons

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