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Question
The mass of one atom of an element X is 2.0 × 10–23 g.
Calculate the atomic mass of element X.
What could element X be ?
Solution
Given:
Mass of an atom of element X = 2.0 × 10-23g
We know that the mass of an atom of a substance is equal to the mass of 1 mole of that substance. 1 mole of a substance consists of 6.022 × 1023 atoms; therefore, the mass of an atom of a substance is equal to the mass of 6.022 × 1023 atoms.
Therefore, to calculate the atomic mass of element X, we need to calculate the mass of 6.022 × 1023 atoms of X.
Mass of 1 atom of X = 2.0 × 10-23
Mass of 6.022 × 1023 atoms of X = 6.022 × 1023 × 2.0 × 10-23 = 12 u
Hence, the atomic mass of element X is 12 u.
Carbon has an atomic mass of 12 u; therefore, element X is carbon.
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