Correct Option
The correct option is 1 and 3 only.
Explanation
The Earth's interior is divided into three main layers: the crust, the mantle, and the core. The core is the innermost layer, distinguished by its high density, specific chemical composition, and distinct physical states across its sub-layers.
Statement-wise Analysis
- Statement 1 is Correct: The boundary separating the mantle from the core is known as the Gutenberg Discontinuity. It is located at a depth of approximately 2,900 km beneath the Earth's surface.
- Statement 2 is Incorrect: The physical states of the core's layers are distinct. The outer core is in a liquid state, which is inferred from the inability of secondary earthquake waves (S-waves) to pass through it. In contrast, the inner core is in a solid state due to the immense pressure exerted by the overlying layers, despite the extremely high temperatures.
- Statement 3 is Correct: The core is composed primarily of heavy metallic materials. It is often referred to as the NIFE layer, indicating the dominance of Nickel (Ni) and Iron (Fe) (Ferrous). This composition contributes to the core's high density and magnetic properties.
Key Takeaway
Key Takeaway: The Earth's core begins at a depth of 2,900 km (Gutenberg Discontinuity) and is composed chiefly of Nickel and Iron (NIFE). The outer core is liquid, while the inner core is solid.