A natural gas has a composition of 92% CH4 , 5% C2H6 , and 3% CO2 by volume. (a) Determine the specific volume of this fuel in m^3/kg and in m^3/kmol at 25*C and 101.3 kPa. (b) Determine the volume of air required in m^3 for stoichiometric combustion of 1m^3 of this fuel. (c) The fuel is burned in a furnace and the products of combustion are found to contain 8% CO2 . Determine the percent excess air used.