Unit 3 - Page 60 - 63

What is the Earth's core mainly composed of?

• Water and gases

• Hot, dense metal

• Solid rock

• Ice and gas

Answer explanation

• Answer: B) Hot, dense metal

• Explanation: The Earth's core is like a giant metal ball made of heavy elements like iron and nickel. It's extremely hot because of the heat left over from the Earth's formation and the heat created by radioactive decay.

• Example: Imagine a metal ball that’s so hot, it’s nearly impossible to touch. That’s the Earth’s core!

What does the lithosphere consist of?

• Only the Earth's mantle

• The crust and upper part of the mantle

• Only the Earth's crust

• Only the Earth's core

Answer explanation

• Answer: B) The crust and upper part of the mantle

• Explanation: The lithosphere is the rigid outer layer of the Earth. It includes the Earth's crust (the outer shell) and the upper part of the mantle (the layer just below the crust). This layer is hard and cool.

• Example: Think of the lithosphere like a hard shell of an egg. The crust is the thin outer part, and the upper mantle is the thicker part right under the shell.

What is the Earth's crust made of?

• Gaseous material

• Dense liquid

• Solid rock

• Liquid metal

Answer explanation

• Answer: C) Solid rock

• Explanation: The Earth's crust is the outermost layer, and it is made of solid rock, like granite and basalt. It’s where we live and find the continents and ocean floors.

• Example: The land you walk on and the ocean floor are part of the Earth's crust.

The mantle is mainly composed of which type of material?

• Solid, dense rock

• Hot, viscous liquid

• Solid and molten rock

• Gaseous substances

Answer explanation

• Answer: C) Solid and molten rock

• Explanation: The mantle is mostly solid, but parts of it are melted and move slowly. It’s like a thick, gooey layer of rock that slowly flows beneath the Earth's crust.

• Example: Imagine a very slow-moving river of thick rock just beneath the Earth's surface.

Which of the following describes continental crust?

• Thicker and less dense than oceanic crust

• Thinner and denser than oceanic crust

• The same thickness as oceanic crust

• Always covered by ocean water

Answer explanation

• Answer: A) Thicker and less dense than oceanic crust

• Explanation: Continental crust is thicker and less dense than oceanic crust. This is why continents stand higher on the Earth's surface than the ocean floor.

• Example: Continental crust is like a thick, light sponge, while oceanic crust is like a thinner, heavier pancake.

What is oceanic crust made of?

• Very dense, dark-colored rock

• Light, porous rock

• Only granite material

• Volcanic rocks

Answer explanation

• Answer: A) Very dense, dark-colored rock

• Explanation: Oceanic crust is made of denser and darker rocks like basalt. It’s thinner compared to continental crust.

• Example: Think of oceanic crust like a dark, heavy rock that lies at the bottom of the oceans.

What is magma?

• Solidified lava

• Hot, molten rock beneath the Earth's surface

• Water from the mantle

• A type of gas emitted by volcanoes

Answer explanation

• Answer: B) Hot, molten rock beneath the Earth's surface

• Explanation: Magma is the melted rock beneath the Earth's surface. When it comes out of a volcano, it’s called lava.

• Example: Magma is like hot soup that’s still inside the pot. Once it pours out, it becomes lava.

What is sea-floor spreading?

• Movement of tectonic plates on land

• The process where new crust forms at mid-ocean ridges and pushes older crust away

• The sinking of crust into the mantle

• Erosion of oceanic crust by water

Answer explanation

• Answer: B) The process where new crust forms at mid-ocean ridges and pushes older crust away

• Explanation: Sea-floor spreading happens at mid-ocean ridges where new oceanic crust forms, and the older crust moves away from the ridge.

• Example: Picture a conveyor belt moving new material in the middle of the ocean and pushing old material aside.

What occurs at a divergent plate boundary?

• Plates collide and one is forced beneath the other

• Plates slide past each other

• Plates move apart, creating new crust

• Plates do not move

Answer explanation

• Answer: C) Plates move apart, creating new crust

• Explanation: At divergent boundaries, tectonic plates move away from each other, creating space where new crust forms.

• Example: Think of a zipper being pulled apart. New material fills the gap in between.

Which boundary involves plates moving towards each other?

• Divergent plate boundary

• Convergent plate boundary

• Conservative plate boundary

• None of the above

Answer explanation

• Answer: B) Convergent plate boundary

• Explanation: At convergent boundaries, plates push into each other. This can lead to the formation of mountains, earthquakes, or volcanic activity.

• Example: It’s like two cars driving toward each other and crashing.