how many grams of c2h6o contain the same number of oxygen atoms as 0.75 mol of h2o?

Answer 1

There is one O in H2O and one O in C2H6O; therefore, 0.75 mol C2H5O will contain the same number of atoms as 0.75 mol H2O.
g C2H6O = mols C2H6O x molar mass C2H6O.