The correct option is 1 and 3 only.
Explanation
The Earth is a differentiated body where materials are arranged in concentric layers based on density. Under the influence of gravity, heavier materials have settled towards the center, while lighter materials reside at the surface and in the atmosphere.
Statement-wise Analysis:
- Statement 1 is Correct: The atmosphere consists of gases, which possess significantly lower density compared to the liquid hydrosphere and the solid lithosphere. While atmospheric density is highest near the surface, it is still negligible compared to the density of rock or metal found in the Earth's interior.
- Statement 2 is Incorrect: The density of Earth's materials increases from the crust to the core. The average density of the crust is approximately 2.7 g/cm³ to 3.0 g/cm³, while the density at the center of the core exceeds 13 g/cm³. This increase is attributed to the heavy metallic composition (Nickel and Iron) of the core and the immense pressure at depth.
- Statement 3 is Correct: The Earth's interior is not homogenous; it is stratified into distinct zones (Crust, Mantle, and Core) with varying material characteristics. These zones differ in chemical composition, density, and physical state (e.g., the outer core is liquid, while the inner core is solid).
Key Takeaway:
Earth's density profile shows a progressive increase with depth, ranging from the least dense atmosphere to the densest metallic Core.