Answer
There are $6.20\times10^{21} molecules$ of naphthalene in the moth ball of 1.32 grams.
Work Step by Step
Using the molar mass of the compound provided, we can simply convert from grams to moles and then from moles to molecules.
$1.32 grams C_{10}H_{8}\times\frac{1 mole C_{10}H_{8}}{128.17 g/mole} = 0.010298821 moles C_{10}H_{8} $
$0.010298821 moles C_{10}H_{8} \times\frac{6.023\times10^{23} atoms C_{10}H_{8} }{1 mole} = 6.20\times10^{21} molecules$
