what is the mass of 4.50 x 10^22 Cu atoms?

Answer 1

4.50 x 10^22 Cu atoms * (1 mol Cu / 6.022 x 10^23 Cu atoms) * 63.546 g Cu/(mol Cu) = 4.7485 g

In every mole of Cu, there are 6.022 x 10^23 atoms (Avogadro's number). The molecular weight of copper is 63.546 g/mol.