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    According to Dobereiner, ___________.
    Question

    According to Dobereiner, ___________.

    A.

    the sum of atomic masses of the first and the third elements of the triad is equal to that of the second element

    B.

    the arithmetical mean of the atomic masses of the first and the third element of the triad is equal to that of the second one

    C.

    the arithmetical mean of the atomic masses of the second and the third element of the triad is equal to that of the first one

    D.

    the sum of atomic masses of the first and the second elements of the triad is equal to that of the third element

    Correct option is B

    Correct Answer: (b) The arithmetical mean of the atomic masses of the first and the third element of the triad is equal to that of the second one

    Explanation:

    • According to Dobereiner's Law of Triads, when elements are grouped into sets of three (called triads) based on their similar chemical properties, the atomic mass of the middle element is approximately the arithmetic mean of the atomic masses of the first and the third elements.

    For example:

    • In the triad of Lithium (Li), Sodium (Na), and Potassium (K): 

    This relationship helped Dobereiner identify patterns in the properties of elements before the development of the periodic table.

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