You have the number of moles n, and the formula for the molecule (which is propane by the way).
The mass can be found using this equation:
[tex]m = nM[/tex]
Now you need to find the molar mass M of propane.
Using the periodic table you can find molar masses in grams per mole of each element. You'll need the molar masses of C and H (since those are the only different atoms present).
[tex]M_C = 12.01g/mol[/tex]
[tex]M_H = 1.01g/mol[/tex]
You can break down the formula into its atoms:
[tex]C_3H_8 = 3C + 8H[/tex]
And same with the molar masses:
[tex]M_{propane} = 3M_C + 8M_H[/tex]
Sub in the values for M of propane.
[tex]M_{propane} = 3(12.01g/mol) + 8(1.01g/mol)[/tex]
[tex]M_{propane} = 36.03g/mol + 8.08g/mol[/tex]
[tex]M_{propane} = 44.11g/mol[/tex]
Finally, use the initial equation for m.
[tex]m = (4.52*10^{-3} mol)(44.11g/mol)[/tex]
[tex]m = 0.2g[/tex]
Hope this helps :)
