A mixture of 60% $N_2$, 30% Ar, and 10% $O_2$ on a mole basis is in a cylinder at 250 kPa and 310 K with a volume of 0.5 $m^3$. Find the mass fractions and the mass of argon.

A mixture of 60% $N_2$, 30% argon, and 10% $O_2$ on a mass basis is in a cylinder at 250 kPa and 310 K with a volume of 0.5 $m^2$. Find the mole fractions and the mass of argon.

A gas mature at $120^{\circ} \mathrm{C}$ and 125 kPa is 50% $N_2$, 30% $H_2O$, and 20% $O_2$ on a mole basis. Find the mass fractions, the mixture has constant, and the volume for 5 kg of mixture.

I want to bring air at $35^{\circ} \mathrm{C}, \Phi=40 \%$, to a state of $25^{\circ} \mathrm{C}, \omega=0.01$. Do I need to add or subtract water?

Explain in words what the absolute and relative humidity expresses?