Geography: Chapter - 2 Interior of the Earth A

Geography: chapter - 2 Interior of the Earth A. Tick the correct option. 1. Obsidian is an example of Ans. Extrusive igneous rock 2. Which of these is not a type of rock? Ans. Magma 3. Metamorphic rocks are formed as a result of Ans. Heat and pressure 4. Which of the following best describes the material that makes up the earth's asthenosphere? Ans. A liquid at a high temperature 5. Nickel and iron are found in the Ans. Core 6. The average radius of the core is Ans. 3500 km B. State True or False. 1. The rocks formed from cooling of lava are intrusive igneous rocks. ( false) 2. The continental crust is referred to as sial ( true) 3. Limestone is a sedimentary rock. ( true) 4. Fossils are found in sedimentary rocks. ( true) 5. The inner core is the hottest part of the earth 's interior. ( true) C. Short- answer questions. 1. How do geologists learn about the earth’s interior? Ans. The geologists learn about the earth’s interior through the study of deep mine operations, earthquake, volcanic eruptions and study of rocks etc. 2. Name the layers of the interior of the earth. Ans. The earth interior is divided into three concentric layers- crust , mantle and core. 3. What are sial and sima? Ans. The continental crust is made up of silica and alumina and hence called sial. The thickness of the oceanic crust is made up of silica and magnesium and hence called sima. 4. why is sial found floating above the mantle? Ans. Sial is less dense so it floats above the mantle. 5. List some used of rocks. Ans. Uses of rocks:

 Graphite is the part of writing.  Slate is used to make blackboard.  Chalk is soft form of limestone. D. Long-answer questions. 1. Explain how igneous rocks are formed. Ans. The word ‘igneous ‘ comes from a Latin word meaning ‘fire’. The molten magma cools to form these types of rocks. They are of two types. The lava cools and hardens to form extrusive igneous rocks. Intrusive igneous rocks are formed when magma cools and crystallizes slowly deep within the earth’s crust. 2. What is rock cycle? Explain it with the help of a labelled diagram. Ans. Rocks are constantly being recycled or being formed, worn down and then formed again. This process is called the rock cycle.

3. How are metamorphic rocks formed? Ans. The word ‘metamorphic means to change form. Metamorphic rocks originate from igneous or sedimentary rocks. Metamorphic rocks are formed deep inside the earth when high temperature and great pressure act on igneous or sedimentary rocks. Metamorphic rocks are denser and stronger. 4. Describe the formation of sedimentary rocks. How do they tell us a lot about the history of the earth? Ans. Sedimentary rocks are usually formed in layers by deposition and compacting of sediments by either cementing or pressure. Sedimentary rocks are the only type of rocks that have fossils and they are formed in layers with the newest rocks on top and the older layers at the bottom. So, they tell us a lot about the history of the earth. 5. Write a short note on minerals. Ans. Minerals are naturally occurring substances found below the earth’’s crust. Metals like iron, copper etc. are extracted from metallic minerals called ores. Non-metallic minerals like petroleum, coal and natural gas are also very useful. E. Draw and label the different layers of the interior of the earth.

F. Match the following. Column A column B 1. Obsidian a. Metamorphic rock ( 5) 2. Sandstone b. Floating rock ( 4) 3. Granite c. Glassy rock ( 1) 4. Pumice d. Sedimentary rock ( 2) 5. Marble e. Igneous rock ( 3) G. Compare and contrast Differentiate between the following 1. Crust and Mantle

Crust Mantle 1. It is top layer of the earth. 1. It is the middle layer of the earth. 2. It is made up of soil, rocks 2. It is made up of dense rocks. And minerals. 2. Inner core and outer core Inner core outer core 1. It is a solid layer . 1. It is a liquid layer . 2. The temperature is estimated 2. The temperature is between 4500°c-6000°C. To be up to 7000°C. 3. Intrusive igneous rocks and Extrusive igneous rock

Intrusive igneous rocks Extrusive igneous rock 1. These are formed when magma 1.The lava cools and hardens to form extrusive igneous Cools and crystallized slowly deep rocks. Within the earth’s crust. 2. A common example is granite 2. Some common examples are basalt, obsidian.