Oops I posted the right question but wrong answer options...

Question

What mass of propane (C3H8) is needed to produce 346g carbon dioxide in the following reaction?
C3H8(g)+5O2(g)->3CO2(g)+4H2O(g)

A. 346g C3H8
B. 115g C3H8
C. 5075g C3H8
D. 1.86g C3H8

Answer 1

You have the equation.
Convert 346 g CO2 to mols. mols = grams/molar mass.
Use the coefficients in the balanced equation to convert mols CO2 to mols propane.
Now convert mols propane to grams. g = mols x molar mass