CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
Which statement best summarizes Earth's structure?
A. Earth is uniform from surface to center
B. Earth consists of layers differing in composition, density and physical state
C. Earth is hollow beneath the crust
D. The mantle and core have identical composition
Correct Answer: B
Earth is differentiated into layers that vary in chemistry, density, temperature, pressure and physical behavior.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The principal evidence that the Earth is layered rather than uniform comes from:
A. Changes in seismic wave behavior with depth
B. Daily weather changes
C. River meanders
D. Cloud formations
Correct Answer: A
Seismic velocities, reflections, refractions and shadow zones reveal distinct internal layers.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
Which sequence lists the major mechanical layers from surface inward?
A. Lithosphere → asthenosphere → mesosphere → outer core → inner core
B. Crust → mantle → atmosphere → core
C. Asthenosphere → lithosphere → crust → core
D. Outer core → mantle → crust → atmosphere
Correct Answer: A
A common mechanical classification is lithosphere, asthenosphere, mesosphere, outer core and inner core.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
Which sequence lists Earth's compositional layers from surface to center?
A. Core → mantle → crust
B. Crust → core → mantle
C. Crust → mantle → core
D. Mantle → crust → core
Correct Answer: C
From the surface inward, the major compositional layers are crust, mantle and core.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
Which pair correctly matches a discontinuity with its boundary?
A. Moho—mantle/outer core
B. Gutenberg—crust/mantle
C. Lehmann—outer core/inner core
D. Conrad—mantle/inner core
Correct Answer: C
The Lehmann discontinuity marks the boundary between the outer and inner core.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The term 'sima' historically refers to relatively silica- and magnesium-rich material associated with:
A. Oceanic/basaltic crustal material
B. Inner core
C. Atmosphere
D. Ice sheets
Correct Answer: A
Sima is an older term for denser silica- and magnesium-rich basaltic material.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The term 'sial' historically refers mainly to the silica- and aluminum-rich part of the:
A. Continental crust
B. Outer core
C. Lower mantle
D. Inner core
Correct Answer: A
Sial is an older term for silica- and aluminum-rich continental crustal material.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
Partial melting in parts of the asthenosphere tends to:
A. Reduce seismic velocities
B. Increase S-wave speed enormously
C. Stop gravity
D. Turn the mantle into a complete ocean of magma
Correct Answer: A
Small amounts of melt and high temperature reduce rigidity and can lower seismic velocities.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
Which layer is most directly associated with the low-velocity zone?
A. Asthenosphere
B. Inner core
C. Lower crust only
D. Outer core
Correct Answer: A
The low-velocity zone occurs in the upper mantle and is commonly associated with the asthenosphere.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
Modern satellite geodesy is especially useful for measuring:
A. Earth's precise shape and gravity field
B. Only cloud cover
C. Only ocean salinity
D. Only rock color
Correct Answer: A
Satellite observations provide precise measurements of Earth's geometry, surface position and gravity variations.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
Which property most directly helps determine the geoid?
A. Gravity potential
B. Air temperature
C. Rainfall
D. Vegetation cover
Correct Answer: A
The geoid is an equipotential surface of Earth's gravity field.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
If Earth stopped rotating, its long-term equilibrium shape would tend to become:
A. More strongly oblate
B. More nearly spherical
C. Prolate
D. Flat
Correct Answer: B
Without rotational centrifugal effects, the equatorial bulge would diminish and Earth would become more nearly spherical.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
Why is Earth's equatorial radius larger than its polar radius?
A. Earth's rotation redistributes mass and produces centrifugal effects
B. The equator has more oceans
C. The poles receive less sunlight
D. The Moon pulls only on the equator
Correct Answer: A
Rotation produces centrifugal acceleration that contributes to equatorial bulging.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
Which statement best distinguishes a geoid from an ellipsoid?
A. A geoid is gravity-based and irregular; an ellipsoid is smooth and mathematical
B. Both are identical everywhere
C. A geoid is a perfect sphere
D. An ellipsoid follows mountains exactly
Correct Answer: A
The geoid follows gravity/equipotential variations, while a reference ellipsoid is a smooth mathematical approximation.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The approximate depth to Earth's center is:
A. 2,900 km
B. 5,150 km
C. 6,371 km
D. 12,756 km
Correct Answer: C
The center is one Earth radius below the surface, about 6,371 km.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
Which part of Earth has the greatest temperature?
A. Upper crust
B. Lower crust
C. Center region
D. Oceanic lithosphere
Correct Answer: C
Temperatures are highest in the deep core and central regions of Earth.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
Which part of Earth has the greatest pressure?
A. Crust
B. Upper mantle
C. Outer core
D. Center of the inner core
Correct Answer: D
Pressure increases inward and is greatest at Earth's center.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
Mantle convection is important because it helps:
A. Drive plate motions and transfer internal heat
B. Stop all seismic waves
C. Flatten the atmosphere
D. Eliminate gravity
Correct Answer: A
Slow mantle convection transfers heat and contributes to plate motions.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
Which internal layer is directly responsible for most plate-tectonic deformation at Earth's surface?
A. Lithosphere
B. Inner core
C. Outer core
D. D'' layer alone
Correct Answer: A
Plate tectonics involves motion and deformation of rigid lithospheric plates.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
P-wave velocity generally increases again when waves enter the:
A. Ocean
B. Inner core
C. Asthenosphere only
D. Crust from mantle
Correct Answer: B
P-wave velocity increases on entering the solid inner core from the liquid outer core.