Why does the earth have a nickel-iron core at its center, surrounded by a silicate mantle? a. silicates are less rigid than metal, so the mantle and crust flowed outward to the exterior b. the core formed first from metallic meteoritesc. a metal core occurs at the center of most planetsd. because it is more dense, the core material sank to the center of the earthe. the intense pressure at the center of the earth caused primordial nebular material to transmutate into metal

d.because it is more dense, the core material sank to the center of the Earth

Explanation:

The nickel-iron core at the center of the earth which is surrounded by very thick layer of mantle silicates results from planetary differentiation.

Planetary differentiation is simply the event that seperated the earth into its different layers. This seggregation is due to the differencies in the density of the materials that formed earth. Heat provided the motion for this seperation and it was sourced from collision between planetissimals and radioactive decay of unstable nuclides.

Nickel and iron occupy the core because of their high density.

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