Answer:
At the high temperatures of the inner solar nebula, the small proto-planets were too hot to hold the volatile gases that dominated the solar nebula. These proto-planets were Earth, Mars, Venus, and Mercury.
Explanation:
The materials that accreted into the early Earth were probably added piecemeal, without and particular order. The early earth was very hot from gravitational compression, impacts and radioactive decay; the earth was partially molted. The denser metallic liquids sank to the center of the Earth and less denser silicate liquids rose to the top. In this way the Earth differentiated very quickly into a metallic, mostly iron core and a rocky silicate mantle.
