Answer
$$5.59 *10^{20} molecules $$
Work Step by Step
From the previous problem, we found that there were 92.9 mmol copper in a penny. Using Avogadro's number, we find:
$$\frac{92.9 mmol}{1} \frac{6.022*10^{23} molecules}{mol} = 5.59 *10^{20} molecules $$
