Which layer surrounding the solid inner core is molten and composed of iron and nickel?

• A. Outer Core
• B. Mantle
• C. Inner Core
• D. Asthenosphere

Answer: (A)

This question tests your understanding of Earth's interior layers and their state and composition around the solid inner core. The layer that surrounds the solid inner core is molten and made of iron and nickel: the outer core. At those depths, temperatures are extremely high, and the iron-nickel alloy remains liquid despite immense pressures, allowing it to flow and convect. This liquid layer drives the geodynamo that generates Earth's magnetic field. Above it lies the mantle, which is solid rock (the upper part includes the asthenosphere, a weak, partially molten zone, but its composition isn’t iron-nickel). The inner core itself stays solid due to the enormous pressures at the center, even though it’s hotter than the outer core.