A soda can is made from aluminum metal. To determine how many atoms of this element is present in a certain mass of the can, we need to convert the mass into units of moles by using the atomic mass of aluminum which is 26.98 g per mol. Then, we use the Avogadro's number. It represents the number of units in one mole of any substance. This has the value of 6.022 x 10^23 units / mole. This number can be used to convert the number of atoms or molecules into number of moles or vice versa.
moles Al = 15.1 g Al ( 1 mol / 26.98 g ) = 0.56 mol Al
atoms Al = 0.56 mol Al ( 6.022x10^23 atoms / 1 mol ) = 3.32x10^23 atoms
OPTION A would be the closest.