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    Question

    Which of the following relation is correct?

    A Number of atoms = (given mass/molar mass) × Avogadro number Correct Answer Incorrect Answer
    B Number of atoms × Avogadro number = given mass/molar mass Correct Answer Incorrect Answer
    C Number of atoms = (molar mass/given mass) × Avogadro number Correct Answer Incorrect Answer
    D Number of atoms = given mass × molar mass × Avogadro number Correct Answer Incorrect Answer

    Solution

    The number of atoms of ANY substance in a volume is: # of atoms = N × (density) × volume / (Molecular Weight). N is a constant called Avogadro's number and its equal to 6.022×1023 atoms/mole. It can also be molecules per mole. Avogadro's number is a proportion that relates molar mass on an atomic scale to physical mass on a human scale. Avogadro's number is defined as the number of elementary particles (molecules, atoms, compounds, etc.) per mole of a substance. It is equal to 6.022 × 1023 mol-1 and is expressed as the symbol NA.

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