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.

Earth's plates move around on the upper mantle.

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

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

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

Answer 1

Accurate:
- "Earth's plates move around on the upper mantle." (They move on the ductile asthenosphere, part of the upper mantle.)
- "Convection currents in Earth's mantle cause Earth's plates to move." (Mantle convection is a main driving mechanism.)

Partly misleading / clarify:
- "Plate tectonics is the theory that Earth's surface is broken into large land masses that move."
Mostly true in spirit, but better phrased: plate tectonics says the lithosphere is broken into rigid plates (oceanic and continental) that move relative to each other — not just "land masses."

Incorrect:
- "Molten rock cools as it nears Earth's crust and sinks back down toward the outer core."
Cooling rock does sink, but it sinks back into the mantle, not down into the outer core.
- "Melted rock from the inner core moves toward Earth's crust because it is less dense."
The inner core is solid (and composed of iron–nickel), and mantle rock does not come from the inner core. Rising material originates in the mantle where hotter, less-dense material rises toward the crust.