Q: Answer the following questions:
a) What are the three layers of the earth ?
Ans: The three layers of the earth are: Crust, Mantle and Core.
b) What is a rock ?
Ans: Any natural mass of mineral matter that makes up the earth’s crust is called a rock.
c) Name three types of rocks.
Ans: Igneous, Sedimentary and Metamorphic.
d) How are extrusive and intrusive rocks formed ?
Ans: Extrusive rocks: When the molten magma comes on the earth’s surface, it rapidly cools down and becomes solid. Rocks formed in such a way on the crust are known as Extrusive rocks.
Intrusive rocks: The intrusive rocks are formed when molten magma cools down deep inside the earth’s crust.
e) What do you mean by a rock cycle ?
Ans: The process of transformation of the rock from one to another is known as a rock cycle.
f) What are the uses of rocks ?
Ans: Rocks are very useful to us. The hard rocks are used for making roads, houses and buildings. Children use rocks to play different games.
g) What are metamorphic rocks ?
Ans: When the igneous and sedimentary rocks undergo great heat and pressure, they change into metamorphic rocks.