Air-methane mixtures can be ignited in the presence of an ignition source if the concentration of methane is between 5.0 and 15.0 mol%. a process in your plant generates a stream of air-methane mixtures at a flow rate of 700.0 kg/h, each at a methane concentration of 9.0 mol%. to eliminate the possibility of a fire, the plant has a protocol for mixing the stream with pure air to reduce the methane concentration to the lower flammability limit (5 mol% methane). a. (16 pts.) calculate the molar flow rate of air (mol/h) required to reduce the concentration to the lower flammability limit. b. (4 pts.) what is the mass fraction of oxygen in the mixture at the lower flammability limit?