How many atoms of gold are in a good nugget w a mass of 4.25 g?

In order to understand and find the answer to the question, there has to be an understanding of what is Avogadro's Number. Avogadro's Number (6.02 × 10²³ particles/mole) represents the number of particles (molecules/atoms) that are in one mole of a substance.
So first, the number of moles of gold need to be calculated
      moles =  mass ÷ molar mass
      moles = 4.25 g ÷ 197 g/mol
      moles = 0.022 mol

    Thus, if     1   mole contains 6.02 × 10²³ particles
Then let 0.022 moles contain     x   particles

⇒       x  =  (6.02 × 10²³) (0.022 mol)

⇒       x  = 1.32 × 10²² particles

Thus the number of atoms of gold in 4.25 g of a gold nugget is 1.32 × 10²² atoms.

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