1

Earth has a magnetic field because of the movement of molten iron and nickel in the liquid outer core. This motion generates electric currents, creating a magnetic field — known as the geodynamo. The magnetic field protects the planet from harmful solar radiation, helps with navigation, and plays a role in animal migration.

2

Earth is approximately 4.54 billion years old. Scientists determine this age using radiometric dating of the oldest rocks on Earth, Moon rocks, and meteorites. These methods measure the decay of radioactive elements over time.

3

The Earth's outer shell is divided into large, moving slabs called tectonic plates. These plates float on a semi-fluid layer beneath them and move due to heat-driven convection currents inside the Earth. Plate movements build mountains, trigger earthquakes, form volcanoes, and create ocean basins.

4

The Earth's core has two layers:

• The outer core is liquid metal (mostly iron and nickel).

• The inner core is solid metal (mostly iron).Scientists know this from studying how seismic waves travel through Earth, as different wave types behave differently in solids and liquids.

5

Earthquakes and volcanoes commonly occur in the same regions because both are associated with tectonic plate boundaries. Subduction zones, rift zones, and fault lines are areas where plates interact, leading to geological activity.

6

If Earth stopped rotating suddenly, the atmosphere and oceans would continue moving, causing massive devastation. One side of the planet would overheat under constant sunlight, while the other would freeze in darkness. The collapse of the magnetic field and changes in day-night cycles would have extreme effects on climate and life.

7

Mountains can still grow if tectonic forces continue to push plates together. For example, the Himalayas are still rising. Over time, erosion wears mountains down, and if tectonic activity ceases, the mountains will eventually flatten.

8

Ocean trenches are formed where one tectonic plate is pushed beneath another (subduction zones), creating deep underwater valleys. Mid-ocean ridges form where plates move apart, allowing magma to rise and solidify into new ocean crust. These features constantly reshape the seafloor.