What is the gas that is often used in chemosynthesis?

Chemosynthesis can be defined as the biological production of organic compounds from C-1 compounds and nutrients, using the energy generated by the oxidation of inorganic (e.g., hydrogen gas, hydrogen sulfide, ammonium) or C-1 organic (e.g., methane, methanol) molecules

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.

the tricuspid valve is present between right atrium and right ventricle