A vessel of volume V contains a mixture of 1 mole of hydrogen and 1 mole of oxygen (both considered ideal). Let f1(v)dv denotes the fraction of molecules with a 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 Maxwell’s distribution law separately.

3. neither f1(v) nor f2(v) will obey Maxwell’s distribution law.

4. f2(v) and f1(v) will be the same.

(2) 
Hint: Apply the concept of Maxwell's distribution law.
For a function f(v), the number of molecules n = f(v), which are having speeds between v and v+dv.
For each function f1(v) and f2(v), n will be different, hence each function f1(v) and f2(v) will obey Maxwell's distribution law separately.