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s and p block elements

5 Class 12 Chemistry questions with answers and explanations.

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All questions with answers
  1. Group IA elements have the outer electron configuration:

    • 1 ns2 np1
    • 2 ns2 np5
    • 3 ns2
    • 4 ns1
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    Correct answer: ns1

    They have one electron in the outer s orbital.

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  2. Which gas is released when sodium reacts with water?

    • 1 Nitrogen
    • 2 Chlorine
    • 3 Hydrogen
    • 4 Oxygen
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    Correct answer: Hydrogen

    2Na + 2H2O gives 2NaOH + H2.

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  3. The most abundant element in the Earth's crust is:

    • 1 Iron
    • 2 Silicon
    • 3 Aluminium
    • 4 Oxygen
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    Correct answer: Oxygen

    Oxygen makes up about 46 percent of the crust by mass.

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  4. Halogens exist as:

    • 1 Diatomic molecules
    • 2 Monatomic gases
    • 3 Metallic solids
    • 4 Triatomic molecules
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    Correct answer: Diatomic molecules

    F2, Cl2, Br2 and I2 are diatomic.

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  5. Noble gases are unreactive because they have:

    • 1 High density
    • 2 Complete outer shells
    • 3 Large size
    • 4 One outer electron
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    Correct answer: Complete outer shells

    Their outer shell is full.

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