2. Calculate the stoichiometric air-fuel ratio for the combustion of a sample of dry anthracite of the following composition by mass: C = 90%; H2=3%; N2 = 1%; Sulphur = 3%; ash = 3%. If 20 per cent excess air is supplied. Determine: (i) Air-fuel ratio (ii) Wet analysis of the products of combustion by volume. 3. The following is the analysis of a supply of coal gas: H = 49.4%; CO = 18% ; CH4 = 20%; C4H8=2%; O2 = 0.4%; N2 = 6.2%; CO2 = 4%. (i) Calculate the stoichiometric A/F ratio. (ii) Find also the wet and dry analyses of the products of combustion if the actual mixture is 20% excess air