Inside Our Earth Class 7 Worksheet Geography Chapter 2

Q.1. What is the radius of earth?

The radius of the earth is 6371 km.

Q.2. What are the three layers of the earth?

The three layers of the Earth are:

• Crust: The outermost layer, which is the thinnest.
• Mantle: Located beneath the crust, extending to about 2900 km deep.
• Core: The innermost layer, consisting of an outer core and an inner core, primarily made of nickel and iron.

Q.3. What are the main mineral constituents of the continental mass?

The main mineral constituents of the continental mass are silica and alumina.

Q.4. What are metamorphic rocks?

Metamorphic rocks are formed when igneous and sedimentary rocks undergo significant heat and pressure. This process transforms them into a new type of rock.

• They can change into different forms, such as:
  • Clay turning into slate
  • Limestone changing into marble
• Metamorphic rocks are often found deep within the Earth.
• They can eventually melt into magma under extreme conditions.

Q.5. Write about the deepest mine in the world.

The deepest mine in the world is located in South Africa. It reaches a depth of approximately 4 km. In the quest for oil, engineers have drilled a hole that is around 6 km deep.

Q.6. What happens to igneous and sedimentary rocks when they are subjected to great heat and pressure?

When subjected to great heat and pressure, igneous and sedimentary rocks transform into metamorphic rocks. This process involves:

• Igneous rocks can change into metamorphic rocks through intense heat and pressure.
• Sedimentary rocks also undergo transformation under similar conditions.
• Examples include clay changing into slate and limestone into marble.

Ultimately, these metamorphic rocks may melt to form molten magma, which can cool and solidify back into igneous rocks.

Q.7. What are the uses of rocks?

Uses of rocks

• The hard rocks are used for making roads, houses and buildings.
• Stones are used in many games. For example, seven stones (pitthoo), hopscotch (stapu/kit kit), five stones (gitti).

Q.8. Sedimentary rocks are formed from sediments. Give reason.

Sedimentary rocks are formed from sediments due to the following processes:

• Rocks break down into smaller pieces through weathering and erosion.
• These small particles, known as sediments, are carried away by natural forces like wind and water.
• As sediments accumulate, they are compressed and hardened over time.
• This process forms distinct layers, resulting in the creation of sedimentary rocks.
• For example, sandstone is formed from grains of sand and may contain fossils.

Q.9. Write a note on various types of rocks?

There are three major types of rocks: igneous rocks, sedimentary rocks and metamorphic rocks.

1. Igneous rocks -When the molten magma cools, it becomes solid. Rocks thus formed are called igneous rocks. They are also called primary rocks. There are two types of igneous rocks: intrusive rocks and extrusive rocks.

• Extrusive igneous rocks - When molten lava comes on the earth’s surface, it rapidly cools down and becomes solid. Rocks formed in such a way on the crust are called extrusive igneous rocks. For example, basalt.
• Intrusive igneous rocks - Sometimes the molten magma cools down deep inside the earth’s crust. Solid rocks so formed are called intrusive igneous rocks. Granite is an example of such a rock.

2. Sedimentary rocks - Rocks roll down, crack, and hit each other and are broken down into small fragments. These smaller particles are called sediments. These sediments are transported and deposited by wind, water, etc. These loose sediments are compressed and hardened to form layers of rocks. These types of rocks are called sedimentary rocks. For example, sandstone is made from grains of sand.

3. Metamorphic rocks - Igneous and sedimentary rocks can change into metamorphic rocks under great heat and pressure. For example, clay changes into slate and limestone into marble.

Q.10. What are igneous rocks?

Igneous rocks are formed when molten magma cools and solidifies. They are also known as primary rocks and can be classified into two types:

• Intrusive rocks: These form when magma cools slowly beneath the Earth's surface, resulting in large grains. An example is granite.
• Extrusive rocks: These form when lava erupts onto the surface and cools quickly, leading to a fine-grained structure. An example is basalt, which makes up the Deccan Plateau.

Q.11. Limestone is changed into marble. Give reason?

Marble is a metamorphic rock that forms when limestone undergoes significant heat and pressure. This process alters the limestone's structure, resulting in the transformation into marble.

Q.12. What do you mean by a rock cycle?

Rock Cycle The rock cycle describes how one type of rock can transform into another through various processes. This transformation occurs in a cyclic manner, involving:

• Igneous rocks form when molten magma cools and solidifies.
• These rocks can break down into small particles, known as sediments.
• Over time, sediments are compressed to form sedimentary rocks.
• Under heat and pressure, both igneous and sedimentary rocks can change into metamorphic rocks.
• If metamorphic rocks melt, they become molten magma again, continuing the cycle.

Q.13. What is the core of the earth made up of?

It is mainly made up of nickel and iron.

Q.14. Name the monument which is made of red sandstone?

The Red Fort is made of red sandstone.

Q.15. What is the Latin word for igneous?

Latin word for igneous is Ignis meaning fire.