Answer:
11 moles Al
Step-by-step explanation:
To find the amount of moles, you need to use Avogadro's number to convert the atoms to moles. Since the value you were given has 2 significant figures, the final answer should also have 2 sig figs.
Avogadro's Number:
6.022 x 10²³ atoms = 1 mole
6.4 x 10²⁴ atoms Al 1 moles
---------------------------- x ------------------------------ = 10.6 moles Al
6.022 x 10²³ atoms
= 11 moles Al