The analysis (by volume) of a supply of gas is as follows: H_2 49.4%;CO18%;CH_4 20%; C_4H_82%;O_20.4%;N_2 6.2% and CO_2 4%. Calculate (i) the stoichiometric Air to Fuel Ratio (ii) the dry analysis of the products of combustion if the actual mixture is 20% weak (i.e. excess air) (iii) the temperature to which the gas must be cooled before condensation of H2O vapour begins, if the pressure in the exhaust is 1.013bar.