Fuels
... Fuels that burn completely make carbon dioxide as a by-product. ... Fossil fuels contain the products of the photosynthesis of plants from millions of years ago. ... This means they are less efficient fossil fuels. ... Suitability of fuels For a fuel to burn, an initial energy source such as a match is needed to break the high-energy bonds in the fuel. ... Size Of Carbon Chain Less energy is required for smaller fuels to burn completely.