Answer: 3.44 *10^22 atoms of Au
Explanation: To solve the number of atoms given the amount of moles can be solved by multiplying the number of moles by Avogadro's numbers, a number that represents the number of atoms in one mole of an element.
Avogradros number is: 6.02214076×10^23 so we do
6.02214076×10²³ * 5.71*10^-2 = # atoms
# atoms = 3.438*10^22 atoms
To simplify to 3 sig figs, it would be 3.44*10^22 since we round the hundradth place.