MCQs on Internal Structure of the Earth – Geography
Q1. Which of the following layers makes up the Earth’s outermost layer?
a. Crust
b. Mantle
c. Outer core
d. Inner core
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Correct Answer: a. Crust
Explanation: The Earth’s crust is the outermost layer, composed of solid rock and varying in thickness from 5 to 70 kilometers.
Q2. Which layer of the Earth is primarily composed of solid rock and makes up about 84% of the Earth’s volume?
a. Crust
b. Mantle
c. Outer core
d. Inner core
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Correct Answer: b. Mantle
Explanation: The mantle is primarily composed of solid rock and makes up about 84% of the Earth’s volume. It extends from the base of the crust to a depth of about 2,900 kilometers.
Q3. Which layer of the Earth is composed of liquid iron and nickel?
a. Crust
b. Mantle
c. Outer core
d. Inner core
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Correct Answer: c. Outer core
Explanation: The outer core is composed of liquid iron and nickel and extends from a depth of about 2,900 kilometers to 5,100 kilometers below the Earth’s surface.
Q4. Which layer of the Earth is composed of solid iron and nickel?
a. Crust
b. Mantle
c. Outer core
d. Inner core
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Correct Answer: d. Inner core
Explanation: The inner core is composed of solid iron and nickel and is located at the center of the Earth, extending from a depth of about 5,100 kilometers to 6,371 kilometers.
Q5. Which of the following is the thinnest layer of the Earth?
a. Crust
b. Mantle
c. Outer core
d. Inner core
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Correct Answer: a. Crust
Explanation: The Earth’s crust is the thinnest layer, varying in thickness from 5 to 70 kilometers.
Q6. Which of the following layers of the Earth is the thickest?
a. Crust
b. Mantle
c. Outer core
d. Inner core
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Correct Answer: b. Mantle
Explanation: The mantle is the thickest layer of the Earth, extending from the base of the crust to a depth of about 2,900 kilometers.
Q7. Which of the following layers of the Earth is the hottest?
a. Crust
b. Mantle
c. Outer core
d. Inner core
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Correct Answer: d. Inner core
Explanation: The inner core is the hottest layer of the Earth, with temperatures estimated to be between 5,000 and 7,000 degrees Celsius.
Q8. Which of the following layers of the Earth is the coolest?
a. Crust
b. Mantle
c. Outer core
d. Inner core
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Correct Answer: a. Crust
Explanation: The Earth’s crust is the coolest layer, with temperatures ranging from the Earth’s surface temperature to about 870 degrees Celsius at its base.
Q9. Which of the following is the boundary between the Earth’s crust and mantle?
a. Mohorovičić discontinuity
b. Gutenberg discontinuity
c. Lehmann discontinuity
d. None of the above
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Correct Answer: a. Mohorovičić discontinuity
Explanation: The Mohorovičić discontinuity, also known as the Moho, is the boundary between the Earth’s crust and mantle. It is characterized by a sudden increase in seismic wave velocities.
Q10. Which of the following is the boundary between the Earth’s mantle and outer core?
a. Mohorovičić discontinuity
b. Gutenberg discontinuity
c. Lehmann discontinuity
d. None of the above
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Correct Answer: b. Gutenberg discontinuity
Explanation: The Gutenberg discontinuity is the boundary between the Earth’s mantle and outer core. It is characterized by a sudden decrease in seismic wave velocities due to the transition from solid mantle to liquid outer core.
Q11. Which of the following is the boundary between the Earth’s outer core and inner core?
a. Mohorovičić discontinuity
b. Gutenberg discontinuity
c. Lehmann discontinuity
d. None of the above
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Correct Answer: c. Lehmann discontinuity
Explanation: The Lehmann discontinuity is the boundary between the Earth’s outer core and inner core. It is characterized by a sudden increase in seismic wave velocities due to the transition from liquid outer core to solid inner core.
Q12. Which of the following layers of the Earth is primarily composed of basaltic rocks?
a. Oceanic crust
b. Continental crust
c. Mantle
d. Outer core
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Correct Answer: a. Oceanic crust
Explanation: The oceanic crust is primarily composed of basaltic rocks, which are formed from the solidification of magma at mid-ocean ridges.
Q13. Which of the following layers of the Earth is primarily composed of granitic rocks?
a. Oceanic crust
b. Continental crust
c. Mantle
d. Outer core
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Correct Answer: b. Continental crust
Explanation: The continental crust is primarily composed of granitic rocks, which are formed from the solidification of magma in the Earth’s crust.
Q14. Which of the following layers of the Earth is denser?
a. Oceanic crust
b. Continental crust
c. Mantle
d. Outer core
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Correct Answer: a. Oceanic crust
Explanation: The oceanic crust is denser than the continental crust due to its composition of basaltic rocks, which have a higher density than the granitic rocks that make up the continental crust.
Q15. Which of the following layers of the Earth is less dense?
a. Oceanic crust
b. Continental crust
c. Mantle
d. Outer core
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Correct Answer: b. Continental crust
Explanation: The continental crust is less dense than the oceanic crust due to its composition of granitic rocks, which have a lower density than the basaltic rocks that make up the oceanic crust.
Q16. Which of the following is a characteristic of the Earth’s lithosphere?
a. Rigid and brittle
b. Partially molten
c. Liquid
d. Solid and ductile
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Correct Answer: a. Rigid and brittle
Explanation: The Earth’s lithosphere is the rigid and brittle outer layer of the Earth, composed of the crust and the uppermost part of the mantle.
Q17. Which of the following is a characteristic of the Earth’s asthenosphere?
a. Rigid and brittle
b. Partially molten
c. Liquid
d. Solid and ductile
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Correct Answer: b. Partially molten
Explanation: The Earth’s asthenosphere is a partially molten layer of the mantle located beneath the lithosphere. It is responsible for the movement of tectonic plates due to its ability to flow and deform.
Q18. Which of the following is a characteristic of the Earth’s mesosphere?
a. Rigid and brittle
b. Partially molten
c. Liquid
d. Decreasing temperature with increasing altitude
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Correct Answer: d. Decreasing temperature with increasing altitude
Explanation: The mesosphere is a layer of Earth’s atmosphere that extends from about 50 to 85 kilometers (31 to 53 miles) above the Earth’s surface. The temperature in the mesosphere decreases with increasing altitude, due to decreasing absorption of solar radiation by the rarefied atmosphere and increasing cooling by CO2 radiative emission.
Q19. Which of the following layers of the Earth is responsible for the movement of tectonic plates?
a. Crust
b. Mantle
c. Asthenosphere
d. Outer core
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Correct Answer: c. Asthenosphere
Explanation: The asthenosphere is a partially molten layer of the mantle located beneath the lithosphere. It is responsible for the movement of tectonic plates due to its ability to flow and deform.
Q20. Which of the following layers of the Earth is the source of Earth’s magnetic field?
a. Crust
b. Mantle
c. Outer core
d. Inner core
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Correct Answer: c. Outer core
Explanation: The Earth’s magnetic field is generated by the movement of liquid iron and nickel in the outer core. The motion of these metals creates electric currents, which in turn produce the magnetic field.