Which statement is true of p- waves ?

a. they travel the fastest through rocks
b. they vibrate at 90 degree to the wave motion
c. they are last to reach the epicenter
d. they are the most damaging

the dark variety, as they are not visible on the dark tree barks

explanation:

oxygen = 21% of the atmosphere

nitrogen = 78%

carbon dioxide = 0.1%

argon =0.934%

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.