Class 9 · Science · Chemistry · Atomic Foundations of Matter

Atomic Number and Mass NumberPractice Questions & MCQs

Practice Atomic Number and Mass Number questions from Atomic Foundations of Matter (Class 9 Science) - important MCQs with answers and step-by-step solutions. Solve the sample questions below, then 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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Atomic Number and Mass Number - Frequently asked questions

Where can I practise Atomic Number and Mass Number questions for Class 9 Science?

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Are these Atomic Number and Mass Number questions important for the exam?

Yes. These Atomic Number and Mass Number important questions follow the Science exam pattern (CBSE Boards, plus JEE and NEET foundation), so they help with both school and competitive prep.

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