Layers of the Earth Questions

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Very Short Answers Questions [1 Mark Questions]

Ques. Which of the following is not true about the Asthenosphere?

1. It is present in the upper mantle
2. It is the source of volcanic activity
3. It is in plastic rather than solid state
4. It is in solid state

Ans. The correct answer is d. It is in solid state

Explanation: It is not in solid form, and the remaining options are true, and they are asthenosphere characteristics. "Asthenes" means "without strength" in Greek, hence the name.

Ques. Which of the following is true about the inner core?

1. It is believed to be a solid body
2. It is believed to be a gaseous body.
3. It is believed to be a semi-solid body
4. It is believed to be a liquid body

Ans. The correct answer is a. It is believed to be a solid body

Explanation: The inner core is thought to be a solid body with a thickness of roughly 1790 kilometers.

Ques. The density of the Earth at its center is said to be

1. 12.7 g/cc
2. 8.8 g/cc
3. 13 g/cc
4. 9.9 g/cc

Ans. The correct answer is c. 13 g/cc

Explanation: The density becomes 12.7 g/cc near the inner core's border and drops to 13 g/cc at the center of the Earth.

Ques. The layer which is said to support the slow-moving tectonic plates is

1. Mohorovic sphere
2. Lithosphere
3. Core layer
4. Asthenosphere

Ans. The correct answer is d. Asthenosphere

Explanation: The Asthenosphere is thought to be entirely located in the upper mantle and is responsible for the slow movement of tectonic plates.

Ques. What is the thickness of the inner core?

1. 2790 km
2. 1790 km
3. 3790 km
4. 790 km

Ans. The correct answer is b. 1790 km

Explanation: The inner core is thought to be solid metallic and has a thickness of roughly 1790 kilometers.

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Short Answers Questions [2 Marks Questions]

Ques. When did different layers of the Earth form?

Ans. Earth was formed more than 4.5 billion years ago. During the early stages of Earth, the entire globe was a ball of scorching matter. The ocean developed once it cooled significantly, and the current layers of solid Earth began to form.

Ques. What are the main constituents of the entire Earth?

Ans. Polar ice, lakes, rivers, and seas include around 71% of the Earth's surface. The rest of the Earth's surface is made up of solid land in the form of islands and continents.

Ques. What is meant by the crust of the Earth?

Ans. The crust is our planet's outermost part, a hardened and cooled layer that ranges in depth from around 5 km to 70 km. Even though it covers the whole surface (ocean bottom and continents), this structure accounts for only 1% of the blue planet's total solid size.

Ques. Explain the upper mantle.

Ans. The upper mantle extends from the crust's edge to a depth of around 410 km. The upper mantle is mostly solid, although its malleable parts cause tectonic activity. The asthenosphere and the lithosphere are two separate portions of the Earth's structure found in the upper mantle.

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Long Answers Questions [3 Marks Questions]

Ques. Explain the lower mantle.

Ans. The depth of the lower mantle ranges between 660 and 2,891 km. 

• The temperature in this region can reach over 4,000 °C near the border with the outer core, which is far higher than the melting point of mantle rocks. 
• Surprisingly, because of the enormous pressure imparted to the mantle, viscosity, and melting are extremely limited in comparison to the outer mantle. 
• It looks to be seismically homogenous, as we know. 
• Aside from that, there is relatively little knowledge of the lower mantle compared to the upper mantle.

Ques. How can the Earth be divided?

Ans. The Earth is classified according to its mechanical and chemical properties. 

• It is classified into the inner core, outer core, mesospheric mantle, asthenosphere, and lithosphere based on mechanical characteristics. 
• Chemical characteristics, on the other hand, separate it into the core (subdivided into the inner core and outer core), the mantle (subdivided into the lower mantle and higher mantle), and the crust. 
• This is the most common division. 
• The structure of the Earth is primarily separated into four major components: the inner core, outer core, mantle, and crust. Each layer has a unique chemical composition and physical features.

Ques. Explain the outer core of the Earth.

Ans. The earth's outer core can be compared to a very hot metal ball. 

• The temperature ranges between 4000 and 9000 degrees Fahrenheit. 
• It is extraordinary, which is why it is entirely liquid. 
• The outer core is located 1800 miles below the crust and is approximately 1400 miles thick. 
• It is made up of metals such as iron and nickel. 
• The outer core does, in fact, encircle the inner core. 
• Because the pressures and temperatures in the inner core are so high, the metals are pushed together and unable to flow freely like liquids, causing them to vibrate rather than solidify.

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Very Long Answers Questions [5 Marks Questions]

Ques. What are the characteristics of the interior of the earth?

Ans. Drilling and mining operations have allowed scientists to examine the earth's interior in order to learn more about it. The following is a list of characteristics based on the available research.

• The temperature rises as one travels closer to the center of the earth.
• The temperature in the center of the Earth is thought to be between 3000 and 5000 degrees Celsius, maybe even higher.
• Because of the massive pressure there, the minerals at the earth's core remain solid even at such high temperatures. 
• As one goes closer to the center of the earth, the pressure rises.
• In the deepest parts of the earth, the pressure is predicted to be 3 to 4 million times that of the atmosphere.
• The density of the earth's layers rises towards the center due to high pressure and temperature, as well as heavier elements such as iron.

Ques. Give a brief description of the evolution of the structure of the Earth.

Ans. The Earth's structure is layered, with an exterior rocky crust and mantle above a molten and solid metal core, however, this interior layered arrangement did not exist early in Earth's history.

• The planet's composition was probably more homogenous earlier in its history. Metals separated from nonmetal substances, and since metals are denser, gravitation pushed them to sink towards the planet's core.
• Similarly, molten material rich in dissolved gases and lighter silica-rich matter is less dense, and it progressively moved higher over time, accumulating in the mantle and thin crust, some of which reached the surface, culminating in volcanism and huge degassing.
• Early crust began to develop despite severe asteroid bombardment.
• The primary divisions of Earth's interior (core, mantle, and crust) were produced by chemical segregation under the effect of gravity. This process also occurred with the Solar System's other planets, moons, and planetesimals.

Ques. Explain the inner core of the Earth.

Ans. It is at the center of the planet and is by far the hottest layer. This inner core is solid, comprised of iron and nickel, and has a temperature of 5,550 degrees Celsius. 

• It serves as Mother Earth's engine room. 
• The fact that iron and other heavy metals can resist such high temperatures is due to the fact that their liquefying temperatures rise considerably at the weights present, which range from roughly 330 to 360 gigapascals. 
• Because the inner core is not inextricably connected to the Earth's strong mantle, it has long been speculated that it may revolve faster or slower than the rest of the planet. 
• Based on seismic wave fluctuations as they flow through the core over decades, researchers estimate that the inner core pivots one degree faster than the surface. 
• Later geophysical analyses estimate the rate of rotation in reference to the surface to be between 0.3 and 0.5 degrees per year.

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