Two types of fuels are alkanes which have the chemical formula C,H2n+2, for n = 1, 2, 3, ... (e.g. methane (CH4), ethane (C;H6), propane (C3Hs) and butane (CH 10)) and alcohols which have the equation C,H2n+2O (e.g. methanol (CH4O, ethanol C,H&O, propanol C3H30 and butanol CAH&0). A burner consumes a fuel which is either an alkane or an alcohol with an Air:Fuel ratio where 20 kmoles of air are used for each kmole of the fuel. A dry analysis of the exhaust gas finds the following percentages by mass: gas % by mass CO2 18.7% CO 3.0% N2 78.3% Write out the combustion equation, including the unknown 'n', and use this to find which fuel is being used. [25 Marks]