The table below shows the fossils found in various layers of an undisturbed rock: fossils in rock layers layer (from top) fossil in layer

1 a, c 2 e 3 a, d, f 4 b 5 f, c 6 d, b

which is most likely an index fossil?

a b d e

answer:

a

explanation:

when, over a long time, layers and layers of sediments get deposited on top of each other, the weight of the top layers presses down on the bottom layers, forming them into rock called sedimentary rock. the oldest layers are on the bottom, and the youngest layers are on the top.

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.