Igneous rocks are formed by the cooling, solidification, and crystallisation of molten magma either beneath the surface or on the surface of the Earth. When magma cools slowly beneath the surface, it forms intrusive igneous rocks with large crystals. When it erupts and cools quickly on the surface as lava, it forms extrusive igneous rocks with fine grains.
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प्रश्न
Describe how igneous rocks are formed.
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उत्तर
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Rock and it's Types
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पाठ 6: Rocks - EXERCISES [पृष्ठ ६४]
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संबंधित प्रश्न
Why is diamond clear and hard while graphite is soft?
How do acidic igneous rocks differ from basic igneous rocks?
What processes are involved in the formation of Igneous Rocks?
Distinguish between the following:
Acid Igneous Rocks and Basic Igneous Rocks.
State the types of rocks for the formation of which the following process is involved.
Decomposition of organic matter at different stages and over different periods of time.
How are sedimentary rocks formed?
Explain the formation of sedimentary rocks on the basis of agents of formation.
Sedimentary rocks are also called stratified rocks. Why?
Classify the following rock: Granite
Classify the following rock: Quartzite
Give one word for the following.
Rocks formed by the cooling and solidification of molten rock from beneath the earth crust.
Fill in the blanks
______ is formed, when the angular and coarse grains of some durable minerals are cemented together.
Give reasons for the following
Silicates are the most common rock forming minerals.
Classify and explain the rocks.
What are fossils?
______ rocks are also called Primary rocks.
Minerals exist in nature ¡n the form of ______ or ______.
Explain Dynamic Metamorphism.
Match the following.
| A. | Basalt | 1. | Anthracite |
| B. | Limestone | 2. | Extrusive igneous |
| C. | Coal | 3. | Metamorphic rock |
| D. | Gneiss | 4. | Sedimentary rock |
Match the following.
| Group A | Group B | ||
| A. | Basalt | 1. | Anthracite |
| B. | Limestone | 2. | Extrusive igneous |
| C. | Coal | 3. | Metamorphic rock |
| D. | Gneiss | 4. | Sedimentary rock |
