Which one of these processes was important for melting the entire Earth about 4.6 billion years ago?
A) heat released by the condensation of water vapor into liquid water to form the ocean
B) radioactivity, or the spontaneous breaking apart of heavier nuclei into lighter ones
C) nuclear fusion, or the combining of lighter nuclei to form heavier ones
D) tidal heating of Earth due to the combined gravitational pulls of the Sun and the Moon

Question

Quizplus · Accepted Answer

Radioactivity was a significant source of heat in the early Earth, contributing to the melting of the entire planet. The decay of radioactive elements within the Earth generated heat, which played a crucial role in its early thermal history.

Which One of These Processes Was Important for Melting the Entire