Chapter 2 - Inside Our Earth Extra Questions
Multiple Choice Questions1. The deepest mine in the world is located in
a) Brazil
b) South Africa
c) India
d) Australia
Answer: b) South Africa
2. The main mineral constituents of the continental mass are
a) silica and alumina
b) silica and magnesium
c) option a) and b)
d) None of these
Answer: a) silica and alumina
3. The radius of the earth is
a) 3671 km
b) 7163 km
c) 6371 km
d) 1736 km
Answer: c) 6371 km
4. The word ignis means
a) water
b) fire
c) oxygen
d) None of these
Answer: b) fire
5. The process of transformation of the rock from one form to another is known as
a) water cycle
b) nitrogen cycle
c) rock cycle
d) all of these
Answer: c) rock cycle
6. Which rock is the molten magma made up of?
a) Igneous
b) Metamorphic
c) Sedimentary
d) None of these
Answer: a) Igneous
7. Rocks which contain fossils are called
a) metamorphic rocks
b) igneous rocks
c) core
d) sedimentary rocks
Answer: d) sedimentary rocks
8. Which one is an example of Sedimentary Rock?
a) sandstone
b) granite
c) marble
d) basalt
Answer: a) sandstone
9. The thinnest layer of the Earth is
a) Crust
b) Mantle
c) Core
d) None of these
Answer: a) Crust
Answer the following questions
10. How are extrusive and Intrusive rocks formed?
Answer:
→ Intrusive Igneous rocks - The igneous rocks formed below the surface of the earth are known as intrusive rocks. These are formed when magma cools and solidifies below the Earth's surface. Example: Granite
→ Extrusive Igneous rocks - The igneous rocks found on the surface of the Earth are known as extrusive rocks. These are formed when the lava cools and solidifies after reaching the Earth's surface during a volcanic eruption. Example: Basalt
11. Define Lava.
Answer: Lava is the hot red magma coming out from the interior of the earth to the surface. It cools down and become solid.
12. What are Fossils?
Answer: The remains of dead plants and animals trapped in the layers of rocks are known as fossils.
13. How are metamorphic rocks formed?
Answer:
• Igneous and Sedimentary rocks changes into metamorphic rocks under heat and pressure.
• When under heat and pressure igneous rocks and sedimentary rocks change their form and more precious rocks are formed to be known as metamorphic rocks.
14. List the uses of rocks.
Answer: The uses of rocks are as follows:
• Hard rocks are used in making buildings.
• Stones are used in games such as phitthoo, Hop scotch, gitti etc.
• Rocks are used in building bridges, embankments etc.
15. Briefly describe the ‘rock cycle’.
Answer: One rock changes into another under certain conditions in a cyclic manner.
Molten magma cools down and solidify to form igneous rocks. These rocks are broken down due to pressure and climatic conditions into sediments. These are transported and deposited to form sedimentary rocks. The igneous and sedimentary rocks under heat and pressure change into metamorphic rocks. These metamorphic rocks under great heat and pressure melt down to form molten magma. This again cools down to form igneous rocks. This process of transformation of rocks is called ‘rock cycle’.
16. What are sedimentary rocks?
Answer: The small particles are called sediments. These small particles are transported and deposited by wind, water etc in low areas. These loose sediments (small particles) are compress and hardened to form layers of rocks. These layers of rocks are called sedimentary rocks. Sedimentary rocks also contain fossils of plants, animals and other micro-organisms.
Fill in the blanks:
17. Crust is about 35 km on the continental mass and 5 km on the ocean floor.
18. The crust forms only 1 per cent of the volume of the earth, 84 per cent consists of the mantle and 15 per cent makes the core.
19. Fossils are the remains of the dead plants and animals trapped in the layers of rocks are called fossils.
20. Igneous and sedimentary rocks can change into metamorphic rocks under great heat and pressure.
21. This process of transformation of the rock from one to another is known as the rock cycle.
22. Minerals are naturally occurring substances which have certain physical properties and definite chemical composition.
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