Answer
$CO_2$ - 6 molecules
$H_2O$ - 8 molecules
$O_2$ - 0 molecules
$C_3H_8$ - 1 molecule
Work Step by Step
$C_3H_8+5O_2\rightarrow 3CO_2+4H_2O$ is the balanced equation.
Oxygen is the limiting reactant, so rewrite the equation using 10 as the coefficient for oxygen. Multiply all coefficients by 2 to keep the equation balanced.
$2C_3H_8+10O_2\rightarrow 6CO_2+8H_2O$
The balanced equation gives you the amount of each product. All the oxygen is consumed so zero molecules remain. Only 2 off the 3 propane molecules were used in the reaction so 1 remains.
