Final answer:
The total amount of matter of the gases after coal is burned remains the same, as dictated by the Law of Conservation of Mass.
Step-by-step explanation:
When coal is burned completely into carbon dioxide and other gases, according to the Law of Conservation of Mass, the total amount of matter of the gases remains the same. The process of burning coal involves a chemical reaction in which coal combines with oxygen to form carbon dioxide. The mass of the coal and the oxygen that reacts with it is equal to the mass of carbon dioxide and other gases produced, implying that matter is neither created nor destroyed during the reaction, only transformed. Even though coal is known for producing more CO₂ per gram of fuel due to its mostly-carbon composition and the absence of hydrogen which can add to energy production without ending up as CO₂, the total mass of the gases remains unchanged after burning.