What is the mole fraction of Ar in the mixture?

a gas, having a molecular weight of 13 kg/kmol and a kinematic viscosity of 0.25 cm2/s, flows through a pipe 0.25 m internal diameter and 5 km long at the rate of 0.4 m3/s and is delivered at atmospheric pressure.

level 4 to level 2 : ))

ok whats the question if not i cannot you i need question and need a thing to answer