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Rocks and rock cycle - class-VIII

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What type of rock is marble?

  1. Volcanic

  2. Metamorphic

  3. Plutonic

  4. Sedimentary


Correct Option: B
Explanation:
  • Marble is formed when limestone is subjected to intense heat and pressure leading to its metamorphism i.e. change in form. Hence marble is called a metamorphic rock

Primary rocks of thermal origin are _________.

  1. Metamorphic rocks

  2. Sedimentary rocks

  3. Igneous rocks

  4. None of these


Correct Option: C
Explanation:

Igneous rocks are called as primary rocks because they originate during the formation of upper crust of the earth on cooling, solidification and crystallization of hot and liquid magmas after the origin of the earth. 

Which of the following rocks is different from the remaining three on the basis of its mode of origin ?

  1. Limestone

  2. Sandstone

  3. Shale

  4. Marble


Correct Option: D
Explanation:

Limestone, Sandstone, and Shale are examples of sedimentary rocks but Marble is an example of metamorphic rock. 

Sedimentary Rocks - These rocks are formed by the accumulation or deposition of small particles and subsequent cementation of minerals or organic particles on the floor of oceans or other bodies of water at the Earth's surface.
Metamorphic rocks - When the physical and chemical properties of the existing rocks get changed due to high heat and pressure, then metamorphic rocks are formed. Marble, slate are examples of metamorphic rocks.

Molten rock below the surface of the earth is called_____________.

  1. Basalt

  2. Laccolith

  3. Lava

  4. Magma


Correct Option: D

Rocks formed by the cooling of the hot masses of the earth or solidification of molten matter are called _______________.

  1. Hard rocks

  2. Igneous rocks

  3. Volcanic rocks

  4. Aqueous rocks


Correct Option: B
Explanation:
  • Igneous rocks are the rocks that are formed by the cooling of hot masses or by the solidification of molten matter, hence option B is correct.
  • Hard rock is any rock that is hard. It is a very general term.
  • Aqueous rocks are the rocks deposited by the water and they get formed in layers or strata.
  • Volcanic rocks are the rocks coming out of the volcanic eruption which are mostly of igneous origin but as already the specific option of Igneous rocks is provided, option D is not the most suitable answer.

Rocks formed by the loose and broken fragments of the pre-existing rocks are called __________________.

  1. Sedimentary rocks

  2. Organic rocks

  3. Soft rocks

  4. Volcanic rocks


Correct Option: A
Explanation:
  • When any rock gets broken it eventually gets eroded and transported to a different place where it settles down in layers. When many layers of such broken materials are piled up and take the form of a rock then it is called a sedimentary rock, hence option A is correct.
  • Soft rock is a general term for any soft rock.
  • Organic rock is a sedimentary rock which has high organic carbon.

Which of the following is not a metamorphic rock?

  1. Marble

  2. Granite

  3. Slate

  4. Quartze


Correct Option: B
Explanation:
  • Marble, Slate and quartz are formed after metamorphism ie change in their original form due to extreme temperatures and pressure.
  • Granite is an igneous rock, thus option B is correct.

If a rock were formed from molten magma, what type of rock is it?

  1. Igneous

  2. Sedimentary

  3. Metamorphic

  4. none of the above


Correct Option: A
Explanation:

Igneous rocks are formed during the formation of the upper crust of the earth on cooling, solidification, and crystallization of hot and liquid magmas after the origin of the earth. Igneous rocks are mostly associated with the volcanic activities and igneous rocks are generally found in the volcanic zones.

Identify the following igneous rock. It has fine grain size and is extrusive.

  1. Granite

  2. Pumice

  3. Both a and b

  4. None of the above


Correct Option: D
Explanation:

None of the above


Extrusive igneous rocks erupt onto the surface, where they cool quickly to form small crystals. Some cool so quickly that they form an amorphous glass. These rocks include andesite, basalt, obsidian, pumice, rhyolite, scoria, and tuff.

Andesite is a fine-grained, extrusive igneous rock composed mainly of plagioclase with other minerals such as hornblende, pyroxene, and biotite.

Rocks like sandstone which allow water to seep through readily are called ______________.

  1. Permeable rocks

  2. Sedimentary rocks

  3. Metamorphic rocks

  4. Mushroom rocks


Correct Option: A
Explanation:
  • Permeable rocks are the rocks having interconnected pores which allow the water to seep through them. Hence option A is correct.
  • Sedimentary rocks and metamorphic rocks are a  broad classification of rocks.
  • Mushroom rocks derive their name out of their shape.

When the lava inside the Earth solidifies, it results in the formation of _______________.

  1. sedimentary rocks

  2. plutonic rocks

  3. volcanic rocks

  4. metamorphic rocks


Correct Option: B
Explanation:
  • When the lava solidifies before reaching the surface, it gives rise to the rocks called plutonic rocks.
  • Volcanic rocks are formed when lava solidifies on the surface of the earth.
  • Sedimentary and metamorphic rocks are not directly related to lava.
  • Hence option B is the correct answer.

Stalactities and stalagmites are most common in ___________.

  1. limestone areas

  2. hard rock areas

  3. snow capped areas

  4. desert areas


Correct Option: A
Explanation:

Stalactites and stalagmites are the depositional landforms of limestone areas. The calcareous deposits from dripping of water in dry caves are called dripstones. The columns of dripstones hanging from the cave ceiling are called stalactites while the calcareous columns of dripstones growing upward from the cave floor are known as stalagmites.

Which of the following statement is not correct :

  1. Black cotton soil of north-west India was formed by the weathering of basaltic lava rocks

  2. Sedimentary rock are distinguished from other types of rocks by the presence of distinct layers

  3. Granite has large cyrstals quartz feldspar and mica in it

  4. A metamorphic rock is softer and less compact than its original type


Correct Option: B

Which of the following is called 'Primary rocks'?

  1. Metamorphic rocks

  2. Sedimentary rocks

  3. Igneous rocks

  4. Stratified rocks


Correct Option: C
Explanation:

Igneous rocks begin the rock cycle, and are therefore called primary rocks. Two major divisions include- volcanic or extrusive rocks that form when magma is ejected from the Earth's crust, and intrusive rocks, which are created below the surface.

Marble is a metamorphic rock. It is formed by the alteration of _________.

  1. granite

  2. coal

  3. graphite

  4. limestone


Correct Option: D

The precious stones line sapphire, ruby, emerald and diamonds are found in ______________ rocks.

  1. chemical sedimentary rocks

  2. metamorphic rocks

  3. igneous rocks

  4. none of these



Correct Option: B

Which one of the landforms is caused by the winds?

  1. Sinkholes

  2. Mushroom rock

  3. Lapies

  4. Headland


Correct Option: B
Explanation:

The rocks having a broad upper part and narrow base resembling an umbrella or mushroom are called mushroom rocks. Mushroom rocks are curved by the erosional work of winds. 

Granite is found in ______________.

  1. Igneous rocks

  2. Sedimentary rocks

  3. Metamorphic rocks

  4. Aqueous rocks


Correct Option: A
Explanation:
  • Granite rock is formed from the cooling of lava so it is found as an igneous rock. Hence option A is correct.
  • Rest options are of different category of rocks.

Quartzite is an example of _________.

  1. igneous rock

  2. sedimentary rocks

  3. metamorphic rocks

  4. none of these


Correct Option: C
Explanation:

Quartzite is a metamorphic rock that is formed by interlocking quartz grains from quartz sandstone. The rock is hard rock, nonfoliated.

Name the rock which is used for making jewellery.

  1. Shale

  2. Pumice

  3. Obsidian

  4. Granite


Correct Option: D
Explanation:

Granite is a light-colored igneous rock. It is composed mainly of quartz and feldspar with a little amount of mica, amphiboles and other minerals. Granite is the world's toughest substance and is used in jewelry making. As few granites are rare and extremely beautiful. They are used as gemstones. Example of granite- blue tint found in the Himalayas etc.

Process of transformation of existing rocks is known as_________.

  1. metamorphism

  2. hypabyssal

  3. abyssalism

  4. all of above


Correct Option: A
Explanation:

The process of transformation of existing rocks is known to be metamorphism.

Which of the following is formed when lava cools on the earth's surface?

  1. Basalt

  2. Granite

  3. Pumice

  4. All of the above


Correct Option: A
Explanation:

Basalt is formed when lava cools on the earth's surface.
Granite is formed when magma cools below the surface of earth.
Pumice is formed by cooling of froth lava on the surface.

Marble is a _________ rocks.

  1. metamorphic

  2. igneous

  3. sedimentary

  4. limestone


Correct Option: A
Explanation:

Marble is formed from the sedimentary rocks. It is also used in making statues.

Which of the following mineral(s) is/are present in granite?

  1. Feldspar

  2. Quartz

  3. Mica

  4. All of the above


Correct Option: D
Explanation:

Feldspar, quartz and mica are the minerals present in granite.
Granite is formed when magma cools below the surface of earth.

Which of the following contains quartz?

  1. Sandstone

  2. Limestone

  3. Shale

  4. Conglomerate


Correct Option: A

Which of the following is/are incorrect statement(s)?

  1. Metamorphic rocks are formed by the transformation of igneous or sedimentary rocks into different kinds of rocks under low temperature but high pressure.

  2. Slate is formed by metamorphosis of limestone.

  3. Marble is formed by metamorphosis of granite.

  4. Gneiss is dark grey shiny rock made by metamorphism of shale. Used to make slates and blackboards.


Correct Option: A,B,C,D
Explanation:

Metamorphic rocks are formed by the transformation of igneous or sedimentary rocks into different kinds of rocks under intense heat and pressure.
Marble is formed by metamorphosis of limestone.
Gneiss is formed by metamorphosis of granite.
Slate is dark grey shiny rock made by metamorphism of shale. Used to make slates and blackboards.

What type of rock is a pumice stone?

  1. Sand stone

  2. Lime stone

  3. Metamorphic rocks

  4. Igneous rocks


Correct Option: D
Explanation:

Pumice is a light volcanic rock. It has a lot of pores in it. It is an igneous rock. The rock is light enough to float on water until it becomes waterlogged. Pumice is a very light rock which is used as body scrubber and to polish floor.

The word 'Igneous' is derieved from the latin word 'ignis' which mean _____________.

  1. soil

  2. cold

  3. magma

  4. fire


Correct Option: D
Explanation:

The word 'igneous' is derived from a Latin word 'ignis' meaning fire. Igneous rocks are known as primary rocks as they are formed through the cooling and solidification of magma or lava. The magma can be derived from partial melts of existing rocks in either a planet's mantle or crust.

Primary rocks are the result of the following process ______________.

  1. Compression

  2. Metamorphism

  3. Solidification

  4. Sedimentation


Correct Option: C
Explanation:

  • Generally, rocks can be divided into three major types based on the process of their formation
  • Igneous rocks are formed by the solidification and cooling of magma in volcanic areas, 
  • While sedimentary rocks are formed by a low-temperature accumulation of sediments in tectonic basins and topographical sinks. 
  • Metamorphic rocks on the other hand are formed by application of temperature and pressure on pre-existing rocks

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