Question 1

Q1: (i) Which one of the following earthquake waves is more destructive? (a) P-waves (b) S-waves (c) Surface waves (d) None of the above

Accepted Answer

Answer: (c) Surface waves Explanation: According to the chapter, surface waves are generated when body waves interact with surface rocks. These waves move along the surface, cause the displacement of rocks, and are responsible for the collapse of structures, making them the most destructive type of...

Question 2

Q2: (ii) Which one of the following is a direct source of information about the interior of the earth? (a) Earthquake waves (b) Volcanoes (c) Gravitationa...

Accepted Answer

Answer: (b) Volcanoes Explanation: The chapter classifies sources of information about the Earth's interior into direct and indirect sources. Volcanic eruptions are a direct source because the molten material (magma) from the interior is thrown onto the surface, where it becomes available for labora...

Question 3

Q3: (iii) Which type of volcanic eruptions have caused Deccan Trap formations? (a) Shield (b) Flood (c) Composite (d) Caldera

Accepted Answer

Answer: (b) Flood Explanation: The text describes Flood Basalt Provinces as volcanoes that outpour highly fluid lava flowing over long distances. It explicitly states, "The Deccan Traps from India, presently covering most of the Maharashtra plateau, are a much larger flood basalt province."

Question 4

Q4: (iv) Which one of the following describes the lithosphere: (a) upper and lower mantle (b) crust and upper mantle (c) crust and core (d) mantle and cor...

Accepted Answer

Answer: (b) crust and upper mantle Explanation: The chapter defines the lithosphere in the section on 'The Mantle'. It states, "The crust and the uppermost part of the mantle are called lithosphere. Its thickness ranges from 10-200 km."

Question 5

Q1: (i) What are body waves?

Accepted Answer

Body waves are earthquake waves that are generated due to the release of energy at the focus of an earthquake. They are named 'body waves' because they travel in all directions through the body of the Earth. There are two types of body waves: P-waves (primary waves) and S-waves (secondary waves).

Question 6

Q2: (ii) Name the direct sources of information about the interior of the earth.

Accepted Answer

The direct sources of information about the interior of the Earth are:    Surface Rocks: The most easily available solid earth material from the surface or from mining areas.    Deep Drilling Projects: Projects like the "Deep Ocean Drilling Project" and the "Integrated Ocean Drilling Project" provid...

Question 7

Q3: (iii) Why do earthquake waves develop shadow zone?

Accepted Answer

Earthquake waves develop a 'shadow zone' because the waves are affected by the different layers of the Earth's interior, particularly the liquid outer core.     S-waves cannot travel through liquid material. Therefore, the liquid outer core blocks S-waves entirely, creating a large shadow zone beyon...

Question 8

Q4: (iv) Briefly explain the indirect sources of information of the interior of the earth other than those of seismic activity.

Accepted Answer

Other than seismic activity, the main indirect sources of information about the Earth's interior are:    Temperature, Pressure, and Density: Analysis shows that temperature, pressure, and density all increase with depth. By studying the rate of this change, scientists can estimate the conditions and...

Question 9

Q1: (i) What are the effects of propagation of earthquake waves on the rock mass through which they travel?

Accepted Answer

The propagation of earthquake waves causes vibrations and exerts different forces on the rock mass through which they travel. The effects vary depending on the type of wave:    P-waves (Primary waves): These waves vibrate parallel to the direction of wave propagation. This movement exerts pressure o...

Question 10

Q2: (ii) What do you understand by intrusive forms? Briefly describe various intrusive forms.

Accepted Answer

Intrusive forms are landforms created when lava released during a volcanic eruption cools and solidifies while still within the Earth's crust, rather than on the surface. These formations, also known as plutonic rocks, only become visible on the surface after the overlying rock has been removed by d...

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