Question

How many grams of C3H18O2 contain 7.9 e25 atoms of Carbon?

Answer 1

Convert atoms of C to molecules C3H18O2. That will be 7.9E25/3 = ? molecules of C
?molecules of C3H18O2/6.02E23 = mols of C3H18O.
g C3H18O2 = mols x molar mass.