Class 7 Chapter 2 Geography

Class 7

Chapter 2 (Geography)

Inside the Earth

Worksheet

Q1. Fill in the blanks:-

1.      The crust is about ____ km on the continents and only_____ km. on the ocean floors. (35 km, 5km)

2.      Beneath the crust lies the ______ which extend to a depth of ____ km. (mantle, 2900 km)

3.      The radius of the earth is _____ km. (6371 km.)

4.      ____ is the thinnest layer of the earth. (crust)

5.      _____% of the earth is crust ______ % is mental and______% core. (1%, 84% and 15%)

Q2. Multiple Choice Questions:-

1.      Fossils includes the remains of _____. (d)

a.      Only Plants   b. animals    c. only fish   d. both plants and animals

2.      Limestone changes into marble when subjected to _______. (b)

a.      heat   b. heat and pressure   c. erosion   d. pressure

3.      The rock which is made up of molten magma is ______. (a)

a.      Igneous   b. Sedimentary   c. Metamorphic   d. All the above

4.      Gold, petroleum, and coal are examples of ______. (b)

a.      Rocks   b. minerals   c. soil    d. none of these

Q3. Match the Column ‘A’ with the Column ‘B’

                        A                                 B

            1. Taj Mahal                            Sandstone                                [4]

            2. Extrusive rocks                    large grained                          [3]

            3. Intrusive rocks                     fine grained                             [2]

            4. Red Fort                               marble                                      [1]

Q4. Answer the following questions in brief (in 1 or 2 lines)

1.     Why limestone is changed into marble?

Ans: Limestone is changed into marble because of heat and pressure.

2.     Why inner core is known as nife?

Ans: The inner core of the earth is known as nife because it is made of nickel and ferrous.

3.     What types of rock is basalt? Where is it found?

Ans: Basalt is a type of extrusive rock. They are found in Deccan plateau.

4.     What are the uses of rocks?

Ans: Rocks are very useful to us. The hard rocks are used for making roads, houses buildings. Rocks provide many type of minerals which are used in kitchen (eg. salt), ornaments (eg. Gold and silver), making vehicles (eg. Iron). We also use many rock stones in many games eg. Pithoo, hop-scotch.  

Q5. Answer the following questions in detail (in 70 to 80 words)

1.      Write difference between intrusive and extrusive rocks.

Ans:

	Intrusive Rocks	Extrusive Rocks
1.	These rocks form when molten magma cools down deep inside the earth crust.	These rocks form when the molten magma comes on the earth surface.
2.	The magma cools very slowly.	The magma cools very rapidly.
3.	They form large grains.	They form fine grains.
4.	Example is Granite.	Example is Basalt found in Deccan Plateau.

2.      What are minerals? How are they derived? Also tell the uses of minerals.

Ans: Minerals are naturally occurring substance which have certain physical properties and definite chemical composition. They are derived from different kind of rocks. Minerals are very useful to humankind. They are used as fuel for vehicles and cooking. For example, coal, natural gas, petroleum etc. they are also used in industries. For example, aluminum, iron, graphite, bauxite, uranium etc. they are also used for making ornaments. For example, gold, silver, diamond etc. they are used in kitchen. For example, salt. They are used in medicines and fertilizers.

3.      Explain rock cycle.

Ans: One type of rock changes to another type under certain conditions in a cyclic manner. This process of transformation of the rock from one to another is known as the rock cycle.

When the molten magma cools; it solidifies to become igneous rock. These igneous rocks are broken down into small particles that are transported and deposited to the sedimentary rocks. When the igneous and sedimentary rocks are subjected to heat and pressure they change into metamorphic rocks. The metamorphic rocks which are still under great heat and pressure melt down to form molten magma. The molten magma again can cool down and solidifies into igneous rocks.