The correct option is 2 only
Explanation
The interior of the Earth is divided into three main concentric layers: the crust, the mantle, and the core. The mantle is the intermediate layer, distinguished by its composition, density, and physical state.
- Statement 1 is Incorrect: The mantle extends from the Mohorovicic discontinuity (Moho), which separates it from the crust, to a depth of approximately 2,900 km. At this depth, the Gutenberg discontinuity marks the boundary between the mantle and the outer core.
- Statement 2 is Correct: The mantle is not in a liquid state. The upper portion of the mantle (asthenosphere) is in a semi-molten or plastic state, allowing lithospheric plates to move. The lower mantle is solid due to the immense pressure exerted by the overlying layers, despite the high temperatures. It is the outer core that is in a liquid state.
- Statement 3 is Incorrect: The density of Earth's layers increases with depth. The crust has a density ranging from approximately 2.7 to 3.0 g/cm³. The mantle is composed of denser materials (rich in magnesium and iron), with a density ranging from approximately 3.4 g/cm³ in the upper mantle to 5.5 g/cm³ in the lower regions. Therefore, the mantle is denser than the crust.
Key Takeaway: The mantle is the solid (though ductile in the upper part) layer between the crust and the core, extending from the Moho to 2,900 km, and is characterized by higher density than the crust but lower density than the core.