Avogadro's number is the number of the particles in a mole of a substance. There are 339 grams of (Rb) rubidium in the sample.
Atoms are the fundamental of the matter that is unsplittable into fine particles.
We know, that 1 mole = 6.022 x 10²³ atoms
So, moles in 2.39 x 10²⁴ atoms will be calculated and converted into mass by using the molar mass of the substance.
2.39 x 10²⁴ × (1 ÷ 6.022 x 10²³) × 85.468 = 339 g Rb
Therefore, 339 g Rb is present in the sample.
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