Answer: IThe primary sources of heat that significantly contributed to the Earth's early molten state are residual heat from the planet's formation and the decay of short-lived isotopes. These sources provided the necessary energy to heat the planet and initiate the process of differentiation, where denser materials sank towards the core while lighter materials rose to form the crust. This led to the formation of the layered structure of the Earth that we observe today.
Step-by-step explanation:
Several sources of heat did not significantly contribute to the Earth's early molten state:
1. Radioactive decay: Radioactive decay refers to the breakdown of unstable isotopes into more stable forms, releasing heat in the process. While radioactive decay does generate heat, it did not significantly contribute to the Earth's early molten state. This is because the concentration of radioactive isotopes was relatively low during the planet's formation, and their contribution to the overall heat budget was minimal.
2. Accretionary heat: Accretionary heat refers to the release of heat during the formation of the Earth through the collision and accretion of smaller celestial bodies. Although accretion did contribute some heat to the early Earth, it did not play a major role in the planet's early molten state. The heat generated from the accretion process dissipated relatively quickly, and other sources of heat had a more significant impact on the Earth's molten state.
3. Gravitational potential energy: During the process of planetary formation, celestial bodies attract and pull materials towards their center due to gravity. This gravitational potential energy is converted into heat. While this source of heat did contribute to the Earth's early molten state, it was not the primary source. Other sources, such as residual heat from the planet's formation and the decay of short-lived isotopes, played more significant roles.