CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The lower mantle is sometimes called the:
A. Mesosphere
B. Troposphere
C. Hydrosphere
D. Photosphere
Correct Answer: A
In mechanical classification, the strong lower mantle is often called the mesosphere.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The asthenosphere is associated with a seismic:
A. High-velocity zone only
B. Low-velocity zone
C. No-wave zone
D. Magnetic zone
Correct Answer: B
Seismic velocities are relatively lower in the asthenosphere, producing the low-velocity zone.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The asthenosphere is best described as:
A. A rigid metallic shell
B. A weak, ductile zone of the upper mantle
C. A liquid ocean beneath the crust
D. A part of the inner core
Correct Answer: B
The asthenosphere is a hot, weak and ductile part of the upper mantle.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The lithosphere moves over the weaker:
A. Inner core
B. Asthenosphere
C. Crust
D. Gutenberg layer
Correct Answer: B
The mechanically weak asthenosphere allows lithospheric plates to move above it.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
Tectonic plates are pieces of the:
A. Asthenosphere only
B. Lithosphere
C. Outer core
D. Lower mantle only
Correct Answer: B
Tectonic plates are rigid sections of the lithosphere.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The mechanical layer consisting of the crust and rigid uppermost mantle is the:
A. Asthenosphere
B. Lithosphere
C. Mesosphere
D. Outer core
Correct Answer: B
The lithosphere includes the crust and the rigid uppermost mantle.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
Which layer contains most of the Earth's mass?
A. Atmosphere
B. Crust
C. Mantle
D. Hydrosphere
Correct Answer: C
The mantle contains roughly two-thirds of Earth's mass, more than any other major layer.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
Which layer occupies the largest proportion of Earth's volume?
A. Crust
B. Mantle
C. Outer core
D. Inner core
Correct Answer: B
The mantle makes up about 84% of Earth's volume.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The process that generates Earth's magnetic field is called the:
A. Geodynamo
B. Geostrophy
C. Isostasy
D. Orogeny
Correct Answer: A
The geodynamo describes magnetic-field generation by convection and rotation in the liquid outer core.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The Earth's magnetic field is generated mainly by:
A. Ocean currents
B. Convection of electrically conducting liquid metal in the outer core
C. Winds in the atmosphere
D. Movement of glaciers
Correct Answer: B
The geodynamo is driven by motion of electrically conducting liquid iron in the outer core.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The inner core remains solid mainly because of:
A. Its low temperature
B. Enormous pressure
C. Lack of iron
D. Absence of gravity
Correct Answer: B
Extreme pressure raises the melting point of iron, keeping the inner core solid despite high temperatures.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The Earth's core is composed chiefly of:
A. Silicon and aluminum
B. Iron and nickel
C. Calcium and sodium
D. Carbon and oxygen
Correct Answer: B
The core is dominated by iron, with nickel and some lighter elements.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The radius of the inner core is approximately:
A. 220 km
B. 620 km
C. 1,220 km
D. 2,220 km
Correct Answer: C
The inner core radius is about 1,220 km.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The inner core begins at a depth of roughly:
A. 2,900 km
B. 4,100 km
C. 5,150 km
D. 6,000 km
Correct Answer: C
The inner core begins at approximately 5,150 km depth.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The boundary between the outer core and inner core is called the:
A. Moho discontinuity
B. Gutenberg discontinuity
C. Lehmann discontinuity
D. Conrad discontinuity
Correct Answer: C
The Lehmann discontinuity separates the liquid outer core from the solid inner core.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The Earth's inner core is primarily:
A. Liquid silicate
B. Solid iron-rich alloy
C. Gaseous iron
D. Basaltic magma
Correct Answer: B
The inner core is solid and consists mainly of iron with nickel and other elements.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The Earth's outer core is primarily:
A. Solid silicate rock
B. Liquid iron-rich alloy
C. Solid ice
D. Molten granite
Correct Answer: B
The outer core is a liquid metallic layer composed mainly of iron with nickel and lighter elements.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The outer core extends approximately from:
A. 35 to 410 km
B. 410 to 660 km
C. 660 to 2,900 km
D. 2,900 to 5,150 km
Correct Answer: D
The liquid outer core extends from about 2,900 km to 5,150 km depth.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The outer core begins at a depth of about:
A. 660 km
B. 1,500 km
C. 2,900 km
D. 5,150 km
Correct Answer: C
The outer core starts at the Gutenberg discontinuity near 2,900 km depth.
CSS - PMS - CCE - PCS - Geography
Earth's Shape and Structure
The core-mantle boundary is known as the:
A. Moho discontinuity
B. Gutenberg discontinuity
C. Lehmann discontinuity
D. Conrad discontinuity
Correct Answer: B
The Gutenberg discontinuity marks the boundary between mantle and outer core at about 2,900 km depth.