The fuel mixer in a natural gas burner mixes methane (CH4) with air to form a combustible mixture at the outlet. Determine the mass flow rates at the two inlets needed to produce 0.01 kg/s of an ideal combustion mixture at the outlet.

Ahe-xe mixture containing a 0.75 mole fraction of helium is used for cooling electronics in an avionics application. at a temperature of 300 k and atmospheric pressure, calculate the mass fraction of helium and the mass density, molar concentration and molecular weight of the mixture. if the cooling capacity is 10 l, what is the mass of the coolant?