Answer
$7.06\times10^{23}\ molecules$
Work Step by Step
Convert grams into moles using the molar mass then multiply by avagadro's number to get the number of molecules.
$389g\ CBr_{4}\times\frac{1mol\ CBr_{4}}{331.63g\ CBr_{4}}\times\frac{6.022\times10^{23}\ molecules}{1\ mol}= 7.06\times10^{23}\ molecules$