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प्रश्न
What is meant by a rock?
उत्तर
A rock can be defined as “an aggregate of minerals that forms a more or less definite unit of the earth’s crust”. A rock does not possess a definite composition like that of a chemical compounds, but is usually a mixture of various minerals.
The bulk of rocks is made up of silica or quartz and feldspar. Feldspar are composed of silica, aluminium, potassium and sodium or calcium. Some rocks are composed of grains cemented together, while several other are crystalline, compact or even glass-like.
All material (whether hard like stone or sand) of which the crust of the earth is composed are called rocks e.g, stone, clay, lava, sand, chalk, salt, coal marble etc.
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संबंधित प्रश्न
Rocks and minerals play a very important role in our lives.
Can you imagine modern life without minerals?
Classify the following rocks by selecting the correct option given below:
gneiss
Name three types of rocks.
Name the rocks which are most widespread on the earth.
Explain this term associated with rocks: Extrusive Igneous Rocks
Describe how are igneous rocks formed? State their chief characteristics.
Classify the igneous rocks on the basis of their place of origin.
Classify the following rock: Peat
Classify the following rock: Limestone
Classify the following rock: Basalt
Give one word for the following.
The outer layer of the earth.
Give one word for the following.
A sedimentary rock, which is composed of microscopically fine, soft and smooth particles.
Fill in the blanks
______ is the best example of the wind deposited stratified rock.
Why are Sedimentary rocks called the Secondary rocks?
Fossils are found in.
______ rocks are also known as stratified rocks.
Minerals exist in nature ¡n the form of ______ or ______.
Intrusive Igneous rocks are also called ______ rocks.
What is lava?
Statement (1): Sedimentary rocks consist of many layers.
Statement (2): Sedimentary rocks are formed by the sediments deposited at different points of time.
