Question

figure 7: model of a mid - oceanic ridge
look at figure 7. what are the two sources of energy that cause the convection currents in the mantle to move the oceanic plates apart?
□ input of solar radiation
□ earthquakes and volcanic eruptions
□ radioactive decay of unstable isotopes
□ residual heat from the formation of the earth

Explanation:

The convection currents driving plate movement at mid-oceanic ridges get their energy from two internal Earth sources: leftover heat from when the Earth formed, and heat released by the radioactive breakdown of unstable isotopes in the mantle. Solar radiation is an external energy source not related to mantle convection, while earthquakes/volcanic eruptions are effects, not energy sources.

Answer:

• radioactive decay of unstable isotopes
• residual heat from the formation of the Earth