Which of the following statements regarding Earth’s internal structure is/are correct?
1. The oceanic crust is heavier than the continental crust.
2. Most of the Earth’s internal heat is contained within the mantle.
3. Large convective cells in the crust circulate heat and drive plate-tectonic processes.
3 only
1 and 2 only
2 and 3 only
1, 2 and 3
Answer is Right!
Answer is Wrong!
This question was previously asked in
UPSC NDA-1 – 2024
Statement 1 is correct. Oceanic crust, primarily composed of basalt, has a higher density (about 3.0 g/cm³) than continental crust, which is mainly granitic in composition (density around 2.7 g/cm³). This difference in density explains why oceanic plates subduct beneath continental plates. Statement 2 is correct. While the Earth’s core is hotter, the mantle, being the largest layer by volume (about 84% of Earth’s volume), contains a significant portion of the Earth’s internal heat, generated from primordial heat and radioactive decay. This heat drives convection within the mantle. Statement 3 is incorrect. Large convective cells responsible for driving plate tectonics are located within the Earth’s *mantle*, not the crust. The crust is the rigid outer shell that is broken into tectonic plates, which move atop the convecting mantle.