Determine the mass in grams of one molecule

Question

1. Determine the number of moles in 75.5g ofAl₂O_3,

a) 3.765mol    b) 3.399 mol

c) 1.750 mol  d) 0.7380 mol

e) 0.667 mol

2. Determine the mass in grams of one molecule of CBr₄     

a)2.60x10^-25g         b) 1.66x10^-24 g

c) 8.63x10^-23g   d) 1.52x10^-22 g  

e) 5.51x10^-22 g