Question

why do convection currents in the asthenosphere cause movement of the lithosphere?
they cool the crust, causing it to shrink and move downward.
they create magnetic fields that pull the crust in different directions.
they transfer heat energy, causing melted material to rise and sink, which moves the plates above.
they push the inner core outward toward the mantle.
question 4
compare the crust, mantle, and core in terms of density and composition. which statement best describes their relationship?
the crust is the densest layer, followed by the mantle, then the core.
density decreases as you move toward the center of the earth.
all layers have the same density but different temperatures.
the core is the densest because it is made of iron and nickel, while the crust is the least dense.

Explanation:

For the first question:

• Convection currents in the asthenosphere transfer heat. Hotter (less - dense) material rises and cooler (more - dense) material sinks. This movement exerts force on the overlying lithospheric plates.
• Option 1: Convection currents in the asthenosphere do not cool the crust to cause it to shrink and move downward. The asthenosphere is part of the mantle (below the crust), and its convection is more about internal heat transfer within the mantle - lithosphere system.
• Option 2: Convection currents in the asthenosphere are not related to creating magnetic fields that pull the crust. The Earth's magnetic field is mainly generated in the outer core (dynamo effect).
• Option 4: Convection currents in the asthenosphere do not push the inner core outward. The inner core is solid and at the center of the Earth, and the asthenosphere is part of the upper mantle.

For the second question:

• The core (especially the inner core) is made of dense materials like iron and nickel. The crust is made of less - dense rocks (e.g., silicate rocks).
• Option 1: The core is denser than the mantle, and the mantle is denser than the crust.
• Option 2: Density increases as you move toward the center of the Earth (core is densest).
• Option 3: The layers have different densities. The core is denser than the mantle, and the mantle is denser than the crust.

Answer:

First question: They transfer heat energy, causing melted material to rise and sink, which moves the plates above.
Second question: The core is the densest because it is made of iron and nickel, while the crust is the least dense.