A liquid fuel mixture consists of 20% ethanol and 80% n-octane (by volume) at 40C. Use the densities of ethanol and n-octane as 785 kg/m' and 698 kg/m', respectively and determine: a) the mole fractions of ethanol and n-octane in the liquid phase, b) the volume fractions of ethanol and n-octane in the vapour phase above the liquid surface at 40C. c) the lower flammability limit of the vapour phase that forms above the liquid surface at 40C.