Convert grams of CF4 to moles by using its molar mass (AKA the masses of all the elements in the compound). Its molar mass is (4(molar mass of F) + 1(molar mass of C)), which is approx. 88.00 grams/mole. Using this, you can set up a proportion or do a quick multiplication using unit analysis, but either way you get about 1.9431 moles.
