Iron is concentrated in earth’s core because of the a. movement of materials due to heating in earth’s protoplanetary phase. b. sequence of accretion of material during earth’s formation. c. radioactive decay of isotopes in earth’s core to produce iron. d. penetration of iron meteorites to earth’s core when earth was smaller than it is now.

The answer is A. During the formation of earth, the friction as elements collided into a mass caused heating, so earth was them constituted majorly of molten lava. The heavier elements like nickel and iron were submerged to the core. This is because, since they are among the heaviest elements, the effect of gravity on them was the greatest.

more words for this could be abiotic and biotic

abiotic: living organisms within an ecosystem

biotic: non-living organisms within an ecosystem

my teacher would say no s