<P> The products of incomplete combustion can be calculated with the aid of a material balance, together with the assumption that the combustion products reach equilibrium . For example, in the combustion of one mole of propane (C) with four moles of O, seven moles of combustion gas are formed, and z is 80% of the stoichiometric value . The three elemental balance equations are: </P> <Ul> <Li> Carbon: a + b = 3 (\ displaystyle a + b = 3) </Li> <Li> Hydrogen: 2 c + 2 d = 8 (\ displaystyle 2c + 2d = 8) </Li> <Li> Oxygen: 2 a + b + c = 8 (\ displaystyle 2a + b + c = 8) </Li> </Ul> <Li> Carbon: a + b = 3 (\ displaystyle a + b = 3) </Li> <Li> Hydrogen: 2 c + 2 d = 8 (\ displaystyle 2c + 2d = 8) </Li>

Name the gas which does not support in burning