Which increases the amount of carbon dioxide in the atmosphere, acting as a carbon source?

The most concentrated carbon dioxide emission are coming from burning of fossil fuels or coal which are very good source of carbon. These fuels have high carbon content which reacts with oxygen gas to produce carbon dioxide when supplied with heat. As what our planet is facing, carbon dioxide gas contributes largely to global warming. These trapped heats can also give enough energy to allow carbon in any organic material to burn and react with oxygen gas in the atmosphere to some extent. Thus, fossil fuels or coals increase the amount of carbon dioxide in the atmosphere that also act as carbon source.

Only one reactant yields 2 or more products. meaning you will only have 1 product and it will break down into 2 or more products. eg. h2o -> h2 + o2