Question

If the terrestrial planets were formed by homogeneous accretion, then which of the following statements is true?

A. They were initially molten, forming an iron core first and accreted a silicate crust later.
B. They were initially molten, forming a silicate core first and accreted an iron crust later.
C. They were initially collections of solid particles that melted, then differentiated into a high-density iron metal core and low-density silicate crust.
D. They were initially collections of solid particles that melted, then differentiated into a high-density silicate core and low-density iron metal crust.

Answer 1

The terrestrial planets were initially collections of solid particles that melted, then differentiated into a high-density iron metal core and low-density silicate crust.

Step-by-step explanation:

The correct statement is option C: they were initially collections of solid particles that melted, then differentiated into a high-density iron metal core and low-density silicate crust.

According to the information provided, during the formation of terrestrial planets, every incoming planetesimal was accelerated by the gravity of the protoplanet, resulting in the melting of both the projectile and a part of the impact area. As a result of the heating, the inner protoplanets experienced planetary differentiation, with heavier metals sinking toward the core and lighter silicates rising toward the surface. This process led to the formation of a high-density iron metal core and a low-density silicate crust.