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
1 pts
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:

• First question: Convection currents in the asthenosphere transfer heat. Hotter (less - dense) material rises and cooler (more - dense) material sinks. This circular motion exerts a force on the overlying lithospheric plates, causing their movement. The other options are incorrect: cooling the crust to shrink it (not the main cause of plate movement), magnetic fields from convection are not the primary cause of plate motion in this context, and pushing the inner core outward is not related to lithospheric plate movement.
• Second question: The core (especially the inner core) is made of dense metals like iron and nickel. The crust is made of lighter silicate rocks. The mantle has an intermediate composition. Density increases towards the center of the Earth. So, the core is the densest (because of iron and nickel composition), and the crust is the least dense. The first option is wrong as the core is denser than the mantle and crust. The second option is incorrect as density increases towards the center. The third option is wrong as layers have different densities.

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.