Question

Select the statement(s) that are accurate about plate tectonics and convection currents.


Plate tectonics is the theory that Earth's surface is broken into large land masses that move.

Convection currents in Earth's mantle cause Earth's plates to move.

Molten rock cools as it nears Earth's crust and sinks back down toward the outer core.

Melted rock from the inner core moves toward Earth's crust because it is less dense.

Earth's plates move around on the upper mantle.

Answer 1

Accurate:
- Convection currents in Earth's mantle cause Earth's plates to move.
- Earth's plates move around on the upper mantle.

Notes on the others:
- "Plate tectonics is the theory that Earth's surface is broken into large land masses that move." — Close but misleading: plate tectonics says the lithosphere is broken into plates (continental and oceanic) that move, not just "land masses."
- "Molten rock cools as it nears Earth's crust and sinks back down toward the outer core." — Incorrect wording: upper-mantle material can cool near the lithosphere and sink back into the mantle, but convection occurs within the mantle (not as a simple melt that sinks all the way to the outer core).
- "Melted rock from the inner core moves toward Earth's crust because it is less dense." — False: the inner core is solid, the source of mantle convection is heat from deeper layers, and mantle convection involves solid-state flow rather than large volumes of “melted rock” from the inner core.