NCERT Solutions for Class 7 Geography Chapter 2 Inside Our Earth contains answers to the exercise questions given in the “Our Environment”. All the answers provided here are accurate and simple that will help you understand the concepts easily and continue your studies without a doubt. These solutions will also help you to score higher marks with the help of well-illustrated answers.
Class 7 Geography Chapter 2 Inside Our Earth Questions and Answers
Question 1: Answer the following questions.
(i) What are the three layers of the earth?
Answer: the three layers of earth are:
- Crust
- Mantle
- Core
(ii) What is a rock?
Answer: Any natural mass of mineral matter that makes up the earth’s crust is called a rock.
(iii) Name three types of rocks.
Answer: the three types of rocks are:
- Igneous Rocks
- Sedimentary Rocks
- Metamorphic Rocks
(iv) How are extrusive and intrusive rocks formed?
Answer: Extrusive rocks are formed by the molten lava which comes out of volcanoes, reaches the earth’s surface and cools down rapidly to become a solid piece of rock. For example, basalt.
When the molten magma cools down deep inside the earth’s crust, the solid rocks so formed are called intrusive rocks. For example, granite.
(v) What do you mean by a rock cycle?
Answer: The process of transformation of rocks from one type to another, due to changes in certain conditions in a cyclic manner, is called a rock cycle.
(vi) What are the uses of rocks?
Answer: Rocks are useful for various purposes:
- It helps in making roads
- It is used in the construction of houses and buildings
- Small stones are used by children in different types of games
- They are used in fertilisers
(vii) What are metamorphic rocks?
Answer: Metamorphic rocks are the rocks that get formed under great heat and pressure. Igneous and sedimentary rocks, when subjected to heat and pressure, get transformed into metamorphic rocks.
Question 2: Tick the correct answer.
(i) The rock which is made up of molten magma is
(a) Igneous
(b) Sedimentary
(c) Metamorphic
Answer: (a) Igneous
(ii) The innermost layer of the earth is
(a) Crust
(b) Core
(c) Mantle
Answer: (b) Core
(iii) Gold, petroleum and coal are examples of
(a) Rocks
(b) Minerals
(c) Fossils
Answer: (b) Minerals
(iv) Rocks which contain fossils are
(a) Sedimentary rocks
(b) Metamorphic rocks
(c) Igneous rocks
Answer: (a) Sedimentary rocks
(v) The thinnest layer of the earth is
(a) Crust
(b) Mantle
(c) Core
Answer: (a) Crust
Question 3: Match the following.
| (i) Core | (a) Earth’s surface |
| (ii) Minerals | (b) Used for roads and buildings |
| (iii) Rocks | (c) Made of silicon and alumina |
| (iv) Clay | (d) Has definite chemical composition |
| (v) Sial | (e) Innermost layer |
| (f) Changes into slate | |
| (g) Process of transformation of the rock Rocks |
Solution:
| (i) Core | (e) Innermost layer |
| (ii) Minerals | (d) Has definite chemical composition |
| (iii) Rocks | (b) Used for roads and buildings |
| (iv) Clay | (f) Changes into slate |
| (v) Sial | (c) Made of silicon and alumina |
Question 4: Give reasons.
(i) We cannot go to the centre of the earth.
Answer: We cannot go to the centre of the earth because the temperature and pressure at the centre of the earth are very high and not just human beings, but even rocks melt at the centre of the Earth.
(ii) Sedimentary rocks are formed from sediments.
Answer: When big rocks break down into small fragments (or sediments), the fragments are transported and deposited by factors like water and wind. The loose sediments compress and harden over the years to form layers and layers of rocks. These rocks are known as sedimentary rocks.
(iii) Limestone is changed into marble
Answer: Igneous and sedimentary rocks change into metamorphic rocks under heat and pressure. Now, limestone is a type of sedimentary rock that under heat and pressure changes into marble which is a metamorphic rock.