Earth Structure — Set 2
Geography · पृथ्वी की संरचना · Questions 11–20 of 50
What is the physical state of the Earth's Outer Core?
Correct Answer: C. Liquid
The Earth's Outer Core is in a liquid state. This is evidenced by the shadow zone of S-waves, which cannot penetrate it. The flow of molten iron in this layer generates Earth's magnetic field.
Despite high temperatures, why is the Inner Core solid?
Correct Answer: B. Immense pressure
The Inner Core remains solid due to immense pressure. Although the temperature is high enough to melt iron, the pressure prevents the atoms from moving into a liquid state. This results in a dense, solid iron-nickel sphere.
Which layer constitutes the largest percentage of the Earth's total volume?
Correct Answer: C. Mantle
The Mantle constitutes the largest volume of the Earth, about 84%. It is the thickest layer, extending from the Moho to the core-mantle boundary. The crust makes up less than 1% of the volume.
How does the density of Earth's materials change as one moves from the surface to the center?
Correct Answer: D. Increases constantly
The density of materials increases as one moves from the surface to the center. The crust is the least dense, while the core is the densest. This stratification occurred due to gravity during Earth's early molten stage.
The Conrad Discontinuity separates which two layers?
Correct Answer: B. Upper Crust and Lower Crust
The Conrad Discontinuity separates the Upper Crust (SIAL) and the Lower Crust (SIMA). It is not found everywhere but is distinct in some continental regions. It marks a transition in seismic wave velocity within the crust.
The Repetti Discontinuity is found between?
Correct Answer: A. Upper Mantle and Lower Mantle
The Repetti Discontinuity separates the Upper Mantle and the Lower Mantle. It is located at a depth of approximately 700 km. It marks a zone of transition where seismic wave velocities change.
The Gutenberg Discontinuity separates which two major layers?
Correct Answer: B. Mantle and Core
The Gutenberg Discontinuity separates the Lower Mantle and the Outer Core. It is located at a depth of about 2,900 km. At this boundary, P-wave velocity drops sharply, and S-waves disappear.
The term 'SIAL' refers to the composition of the upper crust, rich in?
Correct Answer: C. Silica and Aluminum
SIAL stands for Silica and Aluminum. It represents the rocks of the upper continental crust, typically granitic. It is less dense than the underlying layers.
The term 'SIMA' refers to the composition of the lower crust/oceanic crust, rich in?
Correct Answer: D. Silica and Magnesium
SIMA stands for Silica and Magnesium. It represents the rocks of the oceanic crust and lower continental crust, typically basaltic. It is denser than the SIAL layer.
The acronym 'NIFE' is associated with which layer of the Earth?
Correct Answer: D. Core
NIFE stands for Nickel (Ni) and Iron (Fe). It is used to describe the composition of the Earth's Core. These heavy metals provide the core with its high density and magnetic properties.