How much oxygen is required to burn 7m3 of a proton?

We write down the reaction equation, then we equalize it.
C3H8 + 5O2 = 3CO2 + 4H2O.
We calculate the amount of propane substance. We use the following formula.
n = V / Vm.
Where n is the amount of substance.
V is the volume of the substance.
Vm is the molar volume of the substance.
n = 7000 / 22.4 = 312.5 mol.
Further, according to the reaction equation, we find the amount of oxygen.
X mol О2 – 312.5 mol С3Н8.
5 mol О2 – 1 mol С3Н8.
X = 5 * 312.5: 1 = 1562.5 mol.
Next, we find the volume of oxygen.
n = V / Vm.
V = n * Vm.
V = 1562.5 mol * 22.4 l / mol = 35000 l = 35 m’3.
Answer: the volume of oxygen is 35 m’3.