A vessel of volume V contains a mixture of 1 mole of Hydrogen and 1 mole of Oxygen (both considered as ideal). Let f1(v)dv, denote the fraction of molecules with speed between v and (v + dv) with f2 (v)dv, similarly for oxygen. Then
1
f1 (v) + f2 (v) = f (v) obeys the Maxwell’s distribution law
2
f1 (v), f2 (v) will obey the Maxwell’s distribution law separately.
3
Neither f1 (v), nor f2 (v) will obey the Maxwell’s distribution law.
4
f2 (v) and f1 (v) will be the same.