Free Praxis 5005 Practice Test Online

Correct answer: D. Outer core

Correct. The outer core is molten iron and nickel. Seismic S waves, which cannot pass through liquid, are not transmitted through it, which is the main evidence for its liquid state.

• A: The crust is the thin, solid, rocky outer layer.
• B: The inner core is solid iron and nickel, kept solid by the enormous pressure at Earth's center despite its high temperature.
• C: The mantle is solid rock that flows very slowly over long time scales; it is not a liquid.

Correct answer: C. Mantle

Correct. The mantle extends from the base of the crust to a depth of about 2,900 km and makes up roughly 84 percent of Earth's volume.

• A: The outer core is a substantial layer but smaller than the mantle.
• B: The crust is the thinnest layer, only about 5 to 70 km thick.
• D: The inner core is a sphere about 1,200 km in radius, the smallest of the layers.

Correct answer: C. The crust plus the uppermost solid mantle (the lithosphere)

Correct. Tectonic plates are pieces of the lithosphere, which includes the crust and the rigid upper part of the mantle. They ride on the weaker, slowly flowing asthenosphere beneath.

• A: Most of the mantle lies beneath the plates and flows slowly rather than moving as rigid pieces.
• B: The crust alone is too thin to form the plates; the rigid upper mantle is part of each plate.
• D: The outer core is far below the plates and is liquid, not rigid.

Correct answer: C. Divergent

Correct. At a divergent boundary plates move apart, magma rises to fill the gap, and new crust forms. Mid-ocean ridges are the classic example.

• A: Convergent boundaries are where plates collide; they produce trenches and mountain ranges, not new ocean floor.
• B: Subduction happens at convergent boundaries where one plate sinks beneath another; it destroys crust rather than creating it.
• D: Transform boundaries are where plates slide past each other, such as the San Andreas Fault, with no new crust created.

Correct answer: C. A convergent boundary between two continental plates

Correct. When two continental plates collide, neither sinks easily because both are buoyant, so the crust crumples and thickens into high mountains.

• A: Ocean-continent subduction builds volcanic mountain chains such as the Andes; the Himalayas are not volcanic and formed from two continents colliding.
• B: Divergent boundaries pull plates apart and form rift valleys or ridges, not folded mountain ranges.
• D: Transform boundaries slide plates sideways and cause earthquakes but do not build large mountain ranges.