Answer
$8.4 \times 10^{22}$ atoms of Al
Work Step by Step
Number of mole = $\frac{mass}{molar mass} = \frac{3.78}{27} = 0.14$ moles of Al
1 mole = $6.022 \times 10^{23}$ atoms
to convert moles into atoms we multiply the mole value by $6.022 \times 10^{23}$ atoms
= $(0.14) \times (6.022 \times 10^{23})$
= $8.4 \times 10^{22}$ atoms of Al
