Answer
$0.0156$ mole $C_{13}H_{18}O_2$.
Work Step by Step
1. Find the conversion factors that we wil use.
Avogadro's number: $1 \space mole = 6.022 \times 10^{23} \space atoms$.
$\frac{1 \space mole}{6.022 \times 10^{23} \space atoms}$ and $\frac{6.022 \times 10^{23} \space atoms}{1 \space mole}$
According to the subscript in "C": 13 moles $C$ = 1 mole $C_{13}H_{18}O_2$
$\frac{ 13 \space moles \space C}{ 1 \space mole \space C_{13}H_{18}O_2}$ and $\frac{ 1 \space mole \space C_{13}H_{18}O_2}{ 13 \space moles \space C}$
2. Calculate the amount of ibuprofen moles:
$ 1.22 \times 10^{23}$ atoms $C \times \frac{1 \space mole}{6.022 \times 10^{23} \space atoms} \times \frac{ 1 \space mole \space C_{13}H_{18}O_2}{ 13 \space moles \space C} = 0.0156$ mole $C_{13}H_{18}O_2$
