(Exercise Answers)
Q.1) Choose the correct answer.
1. Primary rocks are also known as:
a. igneous rocks
b. sedimentary rocks
c. metamorphic rocks
d. minerals
Ans. a. igneous rocks
2. The oceanic crust consists of:
a. silica and aluminium
b. silica and iron
c. silica and magnesium
d. nickel and iron
Ans. c. silica and magnesium
3. Nife is another name for the:
a. Oceanic crust
b. Continental crust
c. Mantle
d. Core
Ans. d. Core
4. Rocks with a high content of metallic minerals are known as:
a. Fossils
b. Magma
c. ores
d. Lava
Ans. c. ores
B. Fill in the banks:
1. Sial is another name for the ____________. It contains the minerals ________ and ______.
Ans. Earth crust, silica aluminium
2. The innermost layer of the Earth is called the_______.
Ans. core
3. Rock made of cooled Magma is known as _________ rock.
Ans. igneous
4. Hot, molten magma flowing onto the surface of the earth is called __________.
Ans. Lava
5. __________ rocks contain fossils.
Ans. Sedimentary
C. Answer in one or two sentences.
1. Name the three layers of the Earth.
Ans. The three main layers of the Earth are the crust, the mantle and the core.
2. What is the composition of the mantle?
Ans. The mantle lies below the crust. It is composed of the minerals silica, iron, magnesium and aluminium. It makes up more than three - fourths of the Earth's volume.
3. How is the inner core different from the outer core?
Ans. The outer core is liquid, but the inner core is solid as it is under extremely high pressure.
4. What are intrusive rocks?
Ans. Intrusive igneous rocks are formed when magma gets trapped under the crust, cools down and solidifies.
5. Which is the main mineral used in the production of steel?
Ans. The main mineral used in the production of steel is iron ore.
•Civics ch-1 Democracy
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