Quarks are thought to be the basic components

the correct answer, according to e2020, is the second choice there is an occluded front in region a and a cold front in region b.

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 cost of mining is extremely low compared to the money earned from mining, creating income to improve the environment.