Why Do the Terrestrial Planets Have a Much Higher Fraction

question 3

Multiple Choice

Why do the terrestrial planets have a much higher fraction of their mass in heavy chemical elements (as opposed to lighter chemical elements) than the giant planets?

• A) Terrestrial planets are low in mass and high in temperature, thus their lighter chemical elements eventually escaped to the outer reaches of the Solar System.
• B) The heavier elements in the forming solar nebula sank to the center of the Solar System, thus the inner terrestrial planets formed mostly from heavy chemical elements.
• C) The giant planets were more massive than terrestrial planets, and the giant planets preferentially pulled the lighter elements from the inner to the outer Solar System.
• D) Terrestrial planets formed much earlier than giant planets before the hydrogen and helium had a chance to cool and condense onto them.
• E) Terrestrial planets are colder and thus more massive chemical elements condensed on then than the giant planets.