Amodern penny weighs 2.5 g but contains only 0.063 g of copper (cu). how many copper atoms are present in a modern penny?

There are 5.97×10²⁰ atoms of copper in the penny.

From Avogadro's hypothesis, we understood that 1 mole of any substance contains 6.02×10²³ atoms.

This implies that 1 mole of copper, Cu contains 6.02×10²³ atoms.

Recall:

1 mole of copper = 63.55 g

Thus,

Finally, we shall determine the number of atoms present in 0.063 g of copper, Cu. This can be obtained as follow:

63.55 g of Cu = 6.02×10²³ atoms

Therefore,

0.063 g of Cu = 0.063 × 6.02×10²³ / 63.55

Thus, 0.063 g of Cu contains 5.97×10²⁰ atoms

Therefore, we can conclude that there are 5.97×10²⁰ atoms of copper in the penny.

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