Question

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


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.

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

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

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

Answer 1

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

Why the others are not accurate (or need correcting):
- "Molten rock cools as it nears Earth's crust and sinks back down toward the outer core." — Partly describes mantle convection (hot material rises, cools near the base of the lithosphere, then sinks), but mantle rock is mostly solid that slowly flows (not freely molten), and it generally sinks back toward the lower mantle/core–mantle boundary, not specifically into the liquid outer core.
- "Melted rock from the inner core moves toward Earth's crust because it is less dense." — Incorrect: the inner core is solid (the outer core is liquid), and convection of molten material driving plate motion happens in the mantle, not by molten material from the core rising to the crust.
- "Plate tectonics is the theory that Earth's surface is broken into large land masses that move." — Misleading: plate tectonics says the lithosphere is broken into plates (oceanic and continental) that move, not just "large land masses."