In this task, you are given a paragraph, and your job is to generate comma-separated entities present in the given paragraph. Generate entities from a given passage in such a way that (i) they are present in the paragraph, (ii) they are non-duplicate, (iii) they underwent a state change during the process. Avoid creating entities that (i) aren't present in the process paragraph and (ii) aren't significant. 

Fuels burns in the combustion chamber. The burning fuel creates energy. The upward motion cause air to be released into the cylinder. The piston compresses the air. A spark ignites the fuel and air inside the cylinder. The pressure pushes the piston down. The exhaust valve opens. The piston pushes the air out of the cylinder. 
fuel ,air ,spark ,pressure 

Techtonic plates in the earths crust move. Movement creates fissures. Upheavals in the crust. Fissures allow lava to erupt into volcanoes at the surface. Volcanoes erupt, accumulating lava, forming mountains. Upheavals in the crust become their own mountains. 
tectonic plates ,fissures ,upheavals in the crust ,lava ,volcanoes ,mountains ,their own mountains 

A star burns in space. Eventually it burns all its hydrogen. Becomes a red giant. Once the red giant burns itself out. The core of the star collapses. The gasses will start to disperse. Only the core is left. A white dwarf has been formed. 

star ,hydrogen ,red giant ,white dwarf