Answer:
49.86 × 10²³ atoms of Al
Step-by-step explanation:
Given data:
Number of moles of Al = 8.28 mol
Number of atoms = ?
Solution:
The given problem will solve by using Avogadro number. 
It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance. 
The number 6.022 × 10²³ is called Avogadro number. 
For example, 
18 g of water = 1 mole = 6.022 × 10²³ molecules of water 
1.008 g of hydrogen = 1 mole = 6.022 × 10²³ atoms of hydrogen 
For 8.28 moles of Al:
1 mole = 6.022 × 10²³ atoms of Al
8.28 mol×6.022 × 10²³ atoms / 1mol
49.86 × 10²³ atoms of Al