Given :
12.9 mol of Au.
To Find :
How many atoms are in 12.9 moles Au.
Solution :
We know, 1 mol of any element/molecules contains
.
Number of atoms in 12.9 moles of Au is :
![n = 12.9 * 6.022* 10^(23)\ atoms\\\\n = 7.77* 10^(24)\ atoms](https://img.qammunity.org/2021/formulas/chemistry/college/v43t297nutmmk15aow20sw99kyu9e3hyfw.png)
Therefore, number of atoms in 12.9 moles of Au is
.
Hence, this is the required solution.