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Periodic table and periodicity

6 Class 9 Chemistry questions with answers and explanations.

Printable worksheet with answer key

All questions with answers

  1. Elements in the same group of the periodic table have the same number of:

    • 1 Valence electrons
    • 2 Shells
    • 3 Neutrons
    • 4 Protons
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    Correct answer: Valence electrons

    Elements in one group have the same number of valence electrons and so similar properties.

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  2. Group IA elements are called:

    • 1 Alkaline earth metals
    • 2 Alkali metals
    • 3 Halogens
    • 4 Noble gases
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    Correct answer: Alkali metals

    Group IA (lithium, sodium, potassium and so on) are the alkali metals.

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  3. Which of these is a noble gas?

    • 1 Oxygen
    • 2 Neon
    • 3 Sodium
    • 4 Chlorine
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    Correct answer: Neon

    Neon is in group VIIIA with a full outer shell.

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  4. Moving from left to right across a period, the atomic size generally:

    • 1 Stays the same
    • 2 Increases
    • 3 Doubles
    • 4 Decreases
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    Correct answer: Decreases

    The nuclear charge rises while the number of shells stays the same, so atoms get smaller.

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  5. Halogens are found in group:

    • 1 IIA
    • 2 IA
    • 3 VIIA
    • 4 VIIIA
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    Correct answer: VIIA

    Fluorine, chlorine, bromine and iodine are in group VIIA.

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  6. Mendeleev arranged elements in order of increasing:

    • 1 Melting point
    • 2 Atomic mass
    • 3 Density
    • 4 Atomic number
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    Correct answer: Atomic mass

    Mendeleev used atomic mass. The modern table uses atomic number.

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More Chemistry topics
Fundamentals of chemistry
Structure of atoms
Structure of molecules
Physical states of matter
Solutions
Electrochemistry
Chemical reactivity