Q: Decay of what provides some of earth's internal heat?


Read this paragraph and choose the correct option from the provided answers:

Earth's internal heat does not depend on the Sun for energy. This heat comes from remnant heat when the planet formed. It also comes from the decay of radioactive elements. Radioactivity is an important source of energy.

 Choices:

- ionic elements

- decaying elements

- radioactive compounds

- radioactive elements


A:
radioactive elements