It's important to mention that experimental results show that a zero degree Celsius or 273 Kelvin and 1 ATM and pressure 1 mol of any gas, any gas whatsoever, will always correspond to 22.4
liters. And that's because according to our Kinetic Molecular Theory, volume of gas is zero. It's assumed to be zero. And so it doesn't matter what type of gas you use, if it's large or small, it will have a volume of 22.4 liters. Now, this is according to experimental results. Once again, something we observe experimentally, we turn into a theory.