Answer:
6.64x10^23 atoms.
Step-by-step explanation:
From Avogadro's hypothesis, 1 mole of any substance contains 6.02x10^23 atoms. This implies that 1 mole of Cu also contains 6.02x10^23 atoms.
1 mole of Cu = 63.5g
If 63.5g of Cu contains 6.02x10^23 atoms,
Then 70g of Cu will contain = (70x6.02x10^23) /63.5 = 6.64x10^23 atoms.
Therefore, there are 6.64x10^23 atoms in 70g oh Cu