Under STP condition, the gas has a rule of 22.4 L per mole. And according to the ideal gas law, V1/T1=V2/T2. Under STP, 1.5 mol gas has volume of 33.6 L. So the volume under 22 C is 33.6*295/273=36.3 L.
It is how close it is to the noble gasses
No chemical bonding take place.
And the elements or compounds in the mixtures have no definite proportions.