Exercises
1. Answer the following questions.
(i) What are the three layers of the earth?
(ii) What is a rock?
(iii) Name three types of rocks.
(iv) How are extrusive and intrusive rocks formed?
(v) What do you mean by a rock cycle?
(vi) What are the uses of rocks?
(vii) What are metamorphic rocks?
Answers
Answer:
i) The earth is made up of three different layers: the crust, the mantle and the core.
ii) a natural substance composed of solid crystals of different minerals that have been fused together into a solid lump.
iii) igneous, sedimentary, and metamorphic.
iv) Extrusive rocks are formed on the surface of the Earth from lava, which is magma that has emerged from underground. Intrusive rocks are formed from magma that cools and solidifies within the crust of the planet.
v) The rock cycle is a series of processes that create and transform the types of rocks in Earth's crust.
vi) Our use of rocks and minerals includes as building material, cosmetics, cars, roads, and appliances. In order maintain a healthy lifestyle and strengthen the body, humans need to consume minerals
vii) Metamorphic rocks arise from the transformation of existing rock to new types of rock, in a process called metamorphism. The original rock is subjected to temperatures greater than 150 to 200 °C and, often, elevated pressure of 100 megapascals or more, causing profound physical or chemical changes.