Is this true or false - competition is a factor of natural selection

The answer to this is true.

The six principles of natural selection are overpopulation, limited resources, competition, heritable variation, adaptation,  and differential reproductive success.  

 True   competition is a factor of natural selection

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.