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  1. Asked: October 21, 2020In: Class 10

    What were the criteria used by Mendeleev in creating his Periodic Table?

    Best Answer
    ScienceTeacher
    Added an answer on December 5, 2020 at 11:30 am

    Mendeleev’s periodic table was based on the observation that the properties of elements are a periodic function of their atomic masses. This means that if elements are arranged in the increasing order of their atomic masses, then their properties get repeated after regular intervals. For more answerRead more

    Mendeleev’s periodic table was based on the observation that the properties of elements are a periodic function of their atomic masses. This means that if elements are arranged in the increasing order of their atomic masses, then their properties get repeated after regular intervals.

    For more answers visit to website:
    https://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-5/

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  2. Asked: October 21, 2020In: Class 10

    Besides gallium, which other elements have since been discovered that were left by Mendeleev in his Periodic Table? (any two)

    Best Answer
    ScienceTeacher
    Added an answer on December 5, 2020 at 11:29 am

    Scandium and germanium For more answers visit to website: https://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-5/

    Scandium and germanium

    For more answers visit to website:
    https://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-5/

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  3. Asked: October 21, 2020In: Class 10

    Use Mendeleev’s Periodic Table to predict the formulae for the oxides of the following elements: K, C, AI, Si, Ba.

    ScienceTeacher
    Added an answer on December 5, 2020 at 11:28 am

    K is in group 1. Therefore, the oxide will be K₂O. C is in group 4. Therefore, the oxide will be CO₂. Al is in group 3. Therefore, the oxide will be Al₂O₃. Si is in group 4. Therefore, the oxide will be SiO₂. Ba is in group 2. Therefore, the oxide will be BaO. For more answers visit to website: httpRead more

    K is in group 1. Therefore, the oxide will be K₂O.
    C is in group 4. Therefore, the oxide will be CO₂.
    Al is in group 3. Therefore, the oxide will be Al₂O₃.
    Si is in group 4. Therefore, the oxide will be SiO₂.
    Ba is in group 2. Therefore, the oxide will be BaO.

    For more answers visit to website:
    https://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-5/

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  4. Asked: October 21, 2020In: Class 10

    What were the limitations of Newlands’ Law of Octaves?

    Best Answer
    ScienceTeacher
    Added an answer on December 5, 2020 at 11:24 am

    Limitations of Newlands’ law of octaves: a) It was not applicable throughout the arrangements. It was applicable up to calcium only. The properties of the elements listed after calcium showed no resemblance to the properties of the elements above them. b) Those elements that were discovered after NeRead more

    Limitations of Newlands’ law of octaves:
    a) It was not applicable throughout the arrangements. It was applicable up to calcium
    only. The properties of the elements listed after calcium showed no resemblance
    to the properties of the elements above them.
    b) Those elements that were discovered after Newlands’ octaves did not follow the
    law of octaves.
    c) The position of cobalt and nickel in the group of the elements (F, Cl) of different
    properties could not be explained.
    d) Placing of iron far away from cobalt and nickel, which have similar properties as
    iron, could also not be explained.

    For more answers visit to website:
    https://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-5/

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  5. Asked: October 21, 2020In: Class 10

    What were the limitations of Döbereiner’s classification?

    Best Answer
    ScienceTeacher
    Added an answer on December 5, 2020 at 11:24 am

    Limitation of Dobereiner’s classification: All known elements could not be classified into groups of triads on the basis of their properties. For more answers visit to website: https://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-5/

    Limitation of Dobereiner’s classification:
    All known elements could not be classified into groups of triads on the basis of their
    properties.

    For more answers visit to website:
    https://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-5/

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  6. Asked: October 21, 2020In: Class 10

    In the Modern Periodic Table, calcium (atomic number 20) is surrounded by elements with atomic numbers 12, 19, 21 and 38. Which of these have physical and chemical properties resembling calcium?

    Best Answer
    ScienceTeacher
    Added an answer on December 5, 2020 at 11:22 am

    The element with atomic number 12 has same chemical properties as that of calcium. This is because both of them have same number of valence electrons (2). For more answers visit to website: https://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-5/

    The element with atomic number 12 has same chemical properties as that of calcium.
    This is because both of them have same number of valence electrons (2).

    For more answers visit to website:
    https://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-5/

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  7. Asked: October 21, 2020In: Class 10

    How does the electronic configuration of an atom relate to its position in the Modern Periodic Table?

    Best Answer
    ScienceTeacher
    Added an answer on December 5, 2020 at 11:21 am

    In the modern periodic table, atoms with similar electronic configurations are placed in the same column. In a group, the number of valence electrons remains the same. Elements across a period show an increase in the number of valence electrons. For more answers visit to website: https://www.tiwariaRead more

    In the modern periodic table, atoms with similar electronic configurations are placed in the
    same column. In a group, the number of valence electrons remains the same. Elements
    across a period show an increase in the number of valence electrons.

    For more answers visit to website:
    https://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-5/

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  8. Asked: October 21, 2020In: Class 10

    An atom has electronic configuration 2, 8, 7. What is the atomic number of this element?

    Best Answer
    ScienceTeacher
    Added an answer on December 5, 2020 at 11:20 am

    (a) The atomic number of this element is 17. (b) It would be chemically similar to F(9) with configuration as 2, 7. For more answers visit to website: https://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-5/

    (a) The atomic number of this element is 17.
    (b) It would be chemically similar to F(9) with configuration as 2, 7.

    For more answers visit to website:
    https://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-5/

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  9. Asked: October 21, 2020In: Class 10

    What property do all elements in the same column of the Periodic Table as fluorine have in common?

    Best Answer
    ScienceTeacher
    Added an answer on December 5, 2020 at 11:19 am

    All the elements in the same column as fluorine have the same number of valence electrons (7). Hence, they all have valency equal to 1. For more answers visit to website: https://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-5/

    All the elements in the same column as fluorine have the same number of valence
    electrons (7). Hence, they all have valency equal to 1.

    For more answers visit to website:
    https://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-5/

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  10. Asked: October 21, 2020In: Class 10

    What property do all elements in the same column of the Periodic Table as boron have in common ?

    Best Answer
    ScienceTeacher
    Added an answer on December 5, 2020 at 11:17 am

    All the elements in the same column as boron have the same number of valence electrons (3). Hence, they all have valency equal to 3. For more answers visit to website: https://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-5/

    All the elements in the same column as boron have the same number of valence
    electrons (3). Hence, they all have valency equal to 3.

    For more answers visit to website:
    https://www.tiwariacademy.com/ncert-solutions/class-10/science/chapter-5/

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