Question

A piece of Cu weighs 0.635 g. How many atoms of Cu does it contain?

Answer 1

Gram-atomic mass of copper=63.5g

Number of moles in 0.635g of copper=0.63563.5

⇒0.01

Number of copper atoms in 0.01 moles =0.01×6.02×1023

⇒6.02×1021

Answer 2

Solution is above in the attachment