When coal is burned completely into carbon dioxide and other gases, the total amount of matter of the gases
a. is less than the volume of the coal
b. is less than the mass of the coal
c. exceeds the mass of the coal
d. equals the mass of the coal
e. equals half of the volume of the coal

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.