8th Grade Science EOC Test

The correct order of Earth's layers starting from the surface is the crust, mantle, outer core, and inner core. This is because the crust is the outermost layer of the Earth, followed by the mantle, which is a thick layer of hot, solid rock. Below the mantle is the outer core, which is a layer of liquid iron and nickel. Finally, at the center of the Earth is the inner core, which is a solid ball of iron and nickel.

The Earth's inner core is a dense ball of solid metal. This is supported by scientific evidence and theories that suggest the inner core is composed primarily of iron and nickel, which are known to have solid properties under the immense pressure and high temperatures found at the Earth's core. The solid nature of the inner core is also inferred from seismic data, which shows that seismic waves passing through the inner core travel faster than those passing through the surrounding liquid outer core.

The mantle of the Earth is described as a layer of hot rock. This is because the mantle is located between the Earth's crust and the core, and it consists of solid rock that is under high pressure and temperature. The heat in the mantle is generated from the radioactive decay of elements and residual heat from the Earth's formation. This hot rock layer plays a crucial role in the movement of tectonic plates and the convection currents that drive plate tectonics.

P waves, also known as primary waves, are the type of seismic waves that arrive at the surface first. They move by compressing and expanding the ground, similar to how a slinky moves. S waves, on the other hand, are secondary waves that arrive after P waves and move by shaking the ground perpendicular to their direction of travel. Surface waves are a combination of both P and S waves and are responsible for the most damage during an earthquake. Mercalli waves are not a recognized term in seismology.

Surface waves move slower compared to P waves and S waves. P waves, also known as primary waves, are the fastest seismic waves and are the first to be detected after an earthquake. S waves, also known as secondary waves, are slower than P waves but faster than surface waves. Surface waves, on the other hand, are the slowest seismic waves and travel along the Earth's surface, causing most of the damage during an earthquake.

The correct order of the Sun's atmosphere moving away from the center is Photosphere, Chromosphere, Corona. The photosphere is the visible surface of the Sun, followed by the chromosphere which is the layer above the photosphere. The corona is the outermost layer of the Sun's atmosphere.

The correct answer is B. outer core. Earth's magnetic field is generated by the movement of molten iron and nickel in the outer core. This movement, known as convection, is caused by the heat from the inner core. As the molten metal moves, it creates electric currents, which in turn generate a magnetic field. This magnetic field extends out into space and helps protect the Earth from harmful solar radiation.