Question 1: Define crust.
Answer: The uppermost layer over the earth’s surface is called crust.
Question 2: Which mineral is found in the core?
Answer: Nickel and iron
Question 3: What is lava?
Answer: Fiery red molten magma coming out from the interior of the earth on its surface is called lava.
Question 4: Which mineral is found in the crust?
Answer: Silicon, aluminum, magnesium
Question 5: Arrange the following terms from top to bottom based on the order in which they appear in the interior of the earth: mantle, core and crust.
Answer: Crust, Mantle and Core
Question 6: Which layer of the earth is the thinnest?
Question 7: List the minerals that are used as fuels?
Answer: Coal, natural gas, petroleum
Question 8: Which factor is responsible for the difference between extrusive and intrusive rocks?
Answer: The place where the cooling of magma takes place is responsible for the difference between extrusive and intrusive rocks.
Question 9: List the minerals that are used for industrial purposes?
Answer: Gold, aluminium, iron, uranium etc.
Question 10: Why does granite have large grains?
Answer: The slow cooling down of the magma results in large grains in the rocks. Hence, granite has large grains.
Question 11: Give an example of extrusive igneous rock.
Question 1: What are igneous rocks?
Answer: The rocks formed by the solidification, on the cooling of molten magma, are called igneous rocks. They are of two types – intrusive rocks and extrusive rocks.
Question 2: What are minerals?
Answer: Naturally occurring substances which have certain physical properties and a definite chemical composition are called minerals. They are of a great use to mankind, both as a fuel and for industries.
Question 3: What are sedimentary rocks? How are they formed?
Answer: Sedimentary rocks are one of the major types of rocks. These rocks are formed by the hardening and compression of sediments.
Question 4: What are metamorphic rocks?
Answer: The rocks that are formed when the igneous and sedimentary rocks are subjected to great heat and pressure are called metamorphic rocks.
Question 1: Describe the interior of the earth.
Answer: The earth is made up of several concentric layers. The main three layers of the earth are as under:
Question 2: What are rocks? Write in detail about their types.
Answer: Rocks are a natural mass of mineral matter that makes up the earth’s crust. They can be of different colour, size and texture. They are of the following types.
Question 3: Write a short note on minerals.
Answer: Rocks are made up of different minerals. Minerals are naturally occurring substances. They are found on the crust and the core of the earth. They have certain physical properties and have a definite chemical composition. They are very important to humankind. They are used as fuels, for example – coal, petroleum and natural gas. They are used in industries for making medicines, fertlisers and many other items, e.g. iron, aluminium, gold, silver, etc.
Question 4: Describe the rock cycle.
Answer: A cyclic manner is followed in transformation of one type of rock to another type under certain conditions. This process of transformation of rock from one to another is called the rock cycle. When the molten magma cools and solidifies, it forms igneous rocks. These rocks are broken down into small particles that are transported and deposited to form sedimentary rocks. When the igneous and sedimentary rocks are subjected to high heat and pressure, they change into metamorphic rocks. The metamorphic rocks that are still under great heat and pressure, they melt down to form molten magma. This molten magma cools down again and solidifies to form igneous rocks.
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